In 2012, more than one of every four young adults (27 percent) between the ages of 18 and 34 in the United States were without health coverage, according to U.S. Census data. Those 18 million uninsured young adults accounted for 40 percent of the nation’s uninsured population under the age of 65. By comparison, about 20 percent of young adults in Iowa do not have health coverage. Here’s a look at Iowa’s insured population of 18- to 64-year-olds by age and sources of health coverage broken out by household income.