The rate of uninsured American adults declined significantly between 2013 and 2014, according to the Agency for Healthcare Research and Quality (AHRQ).
The percentage of adults ages 18-64 who were uninsured for the entire calendar year fell from 18.8% (35.6 million) in 2013 to 14.4% (27.4 million) in 2014.
For details, see Vistnes and Lipton. (2016). The uninsured in America: Estimates of the percentage of non-elderly adults uninsured throughout each calendar year, by selected population subgroups and state Medicaid expansion status: 2013 and 2014. Statistical Brief #488. Rockville, MD: AHRQ.