38% of Uninsured Make $50,000 or More
The chart above (click to enlarge) is from a study by Robert Ohsfeldt (Texas A&M Health Science Center) and John Schneider (Department of Health Management & Policy, University of Iowa) that supports Greg Mankiw's statement in today's NYTimes that:
"The Census Bureau reports that 18 million of the uninsured have annual household income of more than $50,000, which puts them in the top half of the income distribution."
As the chart shows, more than 38% of the uninsured have incomes of $50,000 or higher. To the extent that these 18 million remained uninsured, we would have to assume that many of them remain uninsured voluntarily (or are self-insured and pay for medical services as needed), since their income levels would certainly indicate that they can afford basic health insurance, but choose not to buy it.