While the total number of uninsured in the United States has fallen by an estimated twenty million since the Affordable Care Act went into effect in 2010, twenty-four million working-age adults remain uninsured, an issue brief from the Commonwealth Fund finds. Based on the Commonwealth Fund Affordable Care Act tracking survey, the issue brief, Who Are the Remaining Uninsured and Why Haven't They Signed Up for Coverage? (20 pages, PDF), found that Latinos now account for 40 percent of the uninsured, up from 29 percent in 2013, while the percentage of white Americans who are uninsured has dropped from roughly 50 percent in 2013 to 41 percent today. The survey also found that 39 percent of the uninsured have incomes below the federal poverty level, and that among uninsured adults who are aware of the state marketplaces or who have tried to enroll for coverage, the majority cited concerns about affordability as a reason for not signing up. Other reasons include the ACA's exclusion of undocumented immigrants, the lack of Medicaid expansion in nineteen states, lower awareness of the marketplaces among certain demographic groups, and the lack of assistance during the enrollment and plan selection process.