According to a recent analysis of Medicare Advantage enrollment patterns:

• 14.4 million Medicare beneficiaries are enrolled in private Medicare Advantage plans, up almost 10% from 2012
• Since 2010, enrollment in Medicare Advantage plans has risen by 30%
• Nationally, about 28% of Medicare beneficiaries are enrolled in Medicare Advantage plans
• The percentage of Medicare beneficiaries enrolled in Medicare Advantage plans ranges from 49% in Minnesota to less than 4% in Iowa and Alaska

Source: "Medicare Advantage 2013 Spotlight: Enrollment Market Update," Mathematica Policy Research Inc/The Kaiser Family Foundation, June 10, 2013, http://kff.org/medicare/issue-brief/medicare-advantage-2013-spotlight-enrollment-market-update/