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Table 1: The 5 Largest Counties by Penetration Group, 2015
State County Medicare Beneficiaries, 2015 Medicare Advantage Penetration Rate, 2015 Average Annual Medicare Advantage Penetration Growth Rate, 2010 -2015

All Counties MA Penetration >50

Florida Miami-Dade 420,702 62% 4%
California Riverside 321,249 57% 4%
Florida Broward 283,971 54% 3%
California San Bernardino 257,419 58% 4%
Pennsylvania Allegheny 247,434 62% 1%
All Counties MA Penetration 40-50%
California Los Angeles 1,344,850 48% 5%
Arizona Maricopa 587,995 43% 0%
California San Diego 463,635 47% 3%
California Orange 443,197 47% 3%
New York Kings 340,846 41% 4%
All Counties MA Penetration 30-40%
Texas Harris 465,027 39% 7%
Michigan Wayne 312,564 32% 16%
Nevada Clark 294,530 39% 2%
Florida Palm Beach 288,386 37% 4%
Texas Dallas 286,947 30% 9%
All Counties MA Penetration 20-30%
Illinois Cook 769,309 23% 20%
New York Suffolk 266,811 21% 5%
Massachusetts Middlesex 248,347 23% 0%
New York Nassau 244,636 24% 4%
New York Westchester 162,885 24% 7%
All Counties MA Penetration 10-20%
New Jersey Bergen 158,800 14% 6%
New Jersey Ocean 142,923 18% 5%
Maryland Montgomery 142,262 10% 5%
Massachusetts Essex 142,201 19% 2%
Illinois DuPage 138,544 17% 29%
All Counties MA Penetration 0-10%
Maryland Baltimore 146,830 9% 0%
Delaware New Castle 89,223 10% 17%
Maryland Anne Arundel 83,847 6% -1%
New Hampshire Hillsborough 69,740 8% 4%
California Monterey 57,418 2% 10%
SOURCE: Kaiser Family Foundation analysis of CMS MA State/County Penetration Files, March 2015.
Table 2: The 50 Largest Counties with the Highest Medicare Advantage Penetration Rate, 2015
Sorted high to low by Medicare Advantage Penetration Rate, 2015
State County Medicare Beneficiaries, 2015 Medicare Advantage Penetration Rate, 2015 Average Annual Medicare Advantage Penetration Growth Rate, 2010 – 2015
Pennsylvania Westmoreland 84,964 66% 1%
New York Monroe 142,272 63% 1%
Pennsylvania Allegheny 247,434 62% 1%
Florida Miami-Dade 420,702 62% 4%
Oregon Clackamas 71,193 61% 1%
California San Bernardino 257,419 58% 4%
Oregon Multnomah 110,238 58% 2%
Oregon Marion 55,898 58% 1%
Oregon Washington 74,146 57% 2%
California Riverside 321,249 57% 4%
Louisiana Jefferson 79,016 57% 3%
New York Erie 185,347 56% 2%
Minnesota Dakota 57,488 55% 5%
Minnesota Hennepin 174,325 55% 4%
Minnesota Ramsey 81,420 55% 4%
Colorado Jefferson 92,064 54% 1%
Washington Clark 73,150 54% 3%
New York Bronx 187,059 54% 5%
Florida Broward 283,971 54% 3%
Florida Pasco 113,780 53% 4%
Colorado Adams 53,543 53% 1%
North Carolina Forsyth 63,689 53% 3%
Ohio Stark 78,836 52% 3%
Florida Hernando 52,948 52% 5%
Ohio Summit 101,919 52% 5%
Ohio Mahoning 52,328 51% 4%
Oregon Lane 73,866 51% 2%
North Carolina Guilford 84,408 50% 7%
Michigan Kent 96,075 50% 9%
Colorado Denver 83,249 50% 2%
New Mexico Bernalillo 111,188 49% 3%
Ohio Montgomery 104,217 49% 4%
Texas El Paso 113,527 49% 9%
Ohio Franklin 162,974 48% 5%
Texas Nueces 53,651 48% 5%
Hawaii Honolulu 165,753 48% 3%
California Los Angeles 1,344,850 48% 5%
California Orange 443,197 47% 3%
Pennsylvania Dauphin 50,092 47% 3%
Florida Polk 133,749 47% 7%
Florida Hillsborough 202,003 47% 4%
California San Diego 463,635 47% 3%
Idaho Ada 62,962 47% 3%
Arizona Pima 187,732 47% 2%
Florida Pinellas 219,663 46% 5%
California Contra Costa 175,189 46% 1%
Florida Volusia 128,192 46% 4%
Louisiana Orleans 55,895 46% 4%
Washington Snohomish 106,900 45% 5%
California Placer 71,991 45% 0%
NOTE: Only counties with more than 50,000 Medicare beneficiaries are included.
SOURCE: Kaiser Family Foundation analysis of CMS MA State/County Penetration Files, March 2015.
Table 3: The 50 Largest Counties with the Lowest Medicare Advantage Penetration Rate, 2015
Sorted low to high by Medicare Advantage Penetration Rate, 2015
State County Medicare Beneficiaries, 2015 Medicare Advantage Penetration Rate, 2015 Average Annual Medicare Advantage Penetration Growth Rate, 2010 – 2015
California Monterey 57,418 2% 10%
Delaware Sussex 56,315 5% 20%
Maryland Anne Arundel 83,847 6% -1%
New Jersey Atlantic 51,231 8% 0%
New Hampshire Rockingham 55,764 8% 5%
New Hampshire Hillsborough 69,740 8% 4%
Maryland Baltimore 146,830 9% 0%
Delaware New Castle 89,223 10% 17%
Maryland Montgomery 142,262 10% 5%
New Jersey Morris 82,111 10% 2%
Massachusetts Barnstable 68,530 11% 4%
Illinois Lake 97,077 12% 34%
California San Luis Obispo 54,536 12% -1%
Virginia Fairfax 132,787 12% 5%
District of Columbia Washington 87,367 13% 6%
Maryland Baltimore City 96,704 13% -1%
California Tulare 56,553 13% 5%
New Jersey Monmouth 111,656 13% 4%
New Jersey Mercer 62,089 14% 3%
New Jersey Bergen 158,800 14% 6%
Maryland Prince George’s 113,587 14% 4%
Massachusetts Plymouth 96,905 14% 0%
California Santa Barbara 69,527 15% -5%
Indiana Lake 85,379 15% 34%
New Jersey Middlesex 122,907 15% 6%
Massachusetts Bristol 110,259 15% 3%
Virginia Va. Beach City 62,735 16% 7%
Alabama Madison 57,237 16% 8%
South Carolina Horry 72,635 16% 11%
New Jersey Burlington 80,871 16% 0%
New York Orange 56,986 17% 13%
Illinois DuPage 138,544 17% 29%
New Jersey Camden 88,147 18% 1%
New York Dutchess 53,869 18% 10%
New Jersey Ocean 142,923 18% 5%
South Carolina Charleston 63,423 18% 11%
New York Rockland 53,270 18% 6%
Connecticut New London 50,507 18% 12%
Arkansas Pulaski 69,860 18% 9%
Massachusetts Norfolk 119,955 18% -1%
New Jersey Passaic 76,897 18% 8%
Massachusetts Essex 142,201 19% 2%
Iowa Polk 65,437 19% 4%
New Jersey Union 80,955 19% 6%
Kansas Sedgwick 78,223 19% 7%
Illinois Will 89,668 19% 33%
South Carolina Richland 56,264 19% 6%
Illinois Kane 66,644 20% 21%
Florida Collier 84,003 21% 13%
New York Suffolk 266,811 21% 5%
NOTE: Only counties with more than 50,000 Medicare beneficiaries are included.
SOURCE: Kaiser Family Foundation analysis of CMS MA State/County Penetration Files, March 2015.
Table 4: The 50 Largest Counties with the Highest Medicare Advantage Average Annual Growth, 2010 – 2015
– Sorted high to low by Average Annual Medicare Advantage Penetration Growth Rate
State County Medicare Beneficiaries, 2015 Medicare Advantage Penetration Rate, 2015 Average Annual Medicare Advantage Penetration Growth Rate, 2010 – 2015
Indiana Lake 85,379 15% 34%
Illinois Lake 97,077 12% 34%
Illinois Will 89,668 19% 33%
Illinois DuPage 138,544 17% 29%
Texas Hidalgo 90,690 35% 25%
Michigan Washtenaw 51,064 28% 23%
Illinois Kane 66,644 20% 21%
Illinois Cook 769,309 23% 20%
Delaware Sussex 56,315 5% 20%
Michigan Macomb 160,039 31% 19%
Michigan Oakland 217,794 31% 18%
Texas Travis 113,201 25% 17%
Delaware New Castle 89,223 10% 17%
Texas Cameron 55,294 38% 16%
Michigan Wayne 312,564 32% 16%
Florida Lake 86,782 32% 15%
North Carolina Mecklenburg 119,517 31% 15%
Florida Citrus 51,772 32% 14%
North Carolina Wake 117,475 31% 14%
Michigan Genesee 83,653 35% 14%
Maine Cumberland 56,599 28% 13%
Florida Collier 84,003 21% 13%
New York Orange 56,986 17% 13%
Florida Sumter 59,153 32% 13%
New York Onondaga 87,400 36% 12%
Connecticut New London 50,507 18% 12%
South Carolina Charleston 63,423 18% 11%
South Carolina Horry 72,635 16% 11%
Florida Sarasota 123,056 26% 11%
California Monterey 57,418 2% 10%
New Jersey Hudson 77,792 22% 10%
Texas Denton 73,775 28% 10%
Massachusetts Suffolk 100,001 22% 10%
Indiana Marion 133,993 27% 10%
Florida Escambia 62,360 28% 10%
New York Dutchess 53,869 18% 10%
Illinois Madison 50,492 30% 10%
North Carolina Buncombe 53,135 25% 10%
Florida Duval 139,652 31% 10%
Texas El Paso 113,527 49% 9%
Wisconsin Milwaukee 145,125 41% 9%
Texas Fort Bend 67,623 33% 9%
Florida Marion 101,107 39% 9%
Connecticut Hartford 160,972 29% 9%
Arkansas Pulaski 69,860 18% 9%
Georgia Fulton 118,697 36% 9%
Georgia DeKalb 89,849 39% 9%
Florida Charlotte 58,326 31% 9%
Georgia Gwinnett 85,751 35% 9%
Tennessee Shelby 135,639 26% 9%
NOTE: Only counties with more than 50,000 Medicare beneficiaries are included.
SOURCE: Kaiser Family Foundation analysis of CMS MA State/County Penetration Files, March 2015.
Table 5: The 50 Largest Counties with the Lowest Medicare Advantage Average Annual Growth, 2010 – 2015
– Sorted low to high by Average Annual Medicare Advantage Penetration Growth Rate
State County Medicare Beneficiaries, 2015 Medicare Advantage Penetration Rate, 2015 Average Annual Medicare Advantage Penetration Growth Rate, 2010 – 2015
California Santa Barbara              69,527 15% -5%
Pennsylvania Montgomery            146,236 27% -3%
California Solano              67,849 39% -2%
Pennsylvania Chester              82,420 24% -2%
Maryland Anne Arundel              83,847 6% -1%
Maryland Baltimore City              96,704 13% -1%
Pennsylvania Bucks            121,609 32% -1%
Pennsylvania Delaware              98,396 28% -1%
California San Luis Obispo              54,536 12% -1%
Massachusetts Norfolk            119,955 18% -1%
Massachusetts Worcester            140,243 35% 0%
Arizona Pinal              66,374 37% 0%
New Jersey Burlington              80,871 16% 0%
New Jersey Atlantic              51,231 8% 0%
California Placer              71,991 45% 0%
Maryland Baltimore            146,830 9% 0%
Massachusetts Middlesex            248,347 23% 0%
Oklahoma Tulsa            100,323 30% 0%
Arizona Maricopa            587,995 43% 0%
Rhode Island Providence            111,469 37% 0%
Pennsylvania Philadelphia            245,320 43% 0%
Massachusetts Plymouth              96,905 14% 0%
California Contra Costa            175,189 46% 1%
Oregon Marion              55,898 58% 1%
California Marin              53,125 36% 1%
California San Mateo            116,237 44% 1%
Pennsylvania Westmoreland              84,964 66% 1%
California Kern            104,434 36% 1%
California Alameda            218,647 42% 1%
New York Richmond              80,747 40% 1%
New York Monroe            142,272 63% 1%
Pennsylvania Allegheny            247,434 62% 1%
New Jersey Camden              88,147 18% 1%
Colorado Adams              53,543 53% 1%
Oregon Clackamas              71,193 61% 1%
California Sacramento            226,661 45% 1%
Colorado Jefferson              92,064 54% 1%
Alabama Jefferson            123,132 43% 1%
Pennsylvania Erie              54,310 45% 1%
Colorado Denver              83,249 50% 2%
Nevada Clark            294,530 39% 2%
Arizona Pima            187,732 47% 2%
Colorado Arapahoe              80,342 44% 2%
Pennsylvania Berks              77,402 34% 2%
Oregon Multnomah            110,238 58% 2%
Oregon Washington              74,146 57% 2%
New York Erie            185,347 56% 2%
Massachusetts Essex            142,201 19% 2%
California Fresno            124,905 30% 2%
California Ventura            129,251 29% 2%
NOTE: Only counties with more than 50,000 Medicare beneficiaries are included.
SOURCE: Kaiser Family Foundation analysis of CMS MA State/County Penetration Files, March 2015.
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