The United States Census Bureau annually reports statistics on the uninsured. The current Census Bureau report states that the number of Americans living uninsured declined to 48.6 million in 2011 from 49.9 million in 2010. The number of persons insured in 2010 increased to 256.2 million from 255.3 million in 2009. According to its most recent figures, in 2009 there were 50.7 million people in the US (16.7% of the population) who were without health insurance. This is up from 2008, when there were 46.3 million people in the US (15.4% of the population) who were without health insurance. The percentage of the non-elderly population who are uninsured has been generally increasing since the year 2000. However, the 2007 figures were down slightly from the Census Bureau reports for the previous year, because 3 million more people received coverage under government programs.
A study published in 2009 by the journal Health Affairs found that the Census Bureau estimates, which are based on the Current Population Survey, under count Medicaid enrollment. As a result, it likely overstates the number of uninsured individuals.
The number of people who lack insurance at some time during a multi-year period is greater than the number currently uninsured. A study published by Families USA in 2009 estimated that approximately 86.7 million people were uninsured at some point during the two-year period 2007-2008. This represented about 29% of the total US population or about one-in-three under 65 years of age.