The Gallup-Healthways Well-Being Index was based on 19,293 interviews with U.S. adults from Jan. 2 to Feb. 10.
The percentage of those uninsured ages 26 to 34, which has been dropping since the third quarter of 2013, is now 25.7 percent. Americans in this age group have had the highest uninsured rate since 2011. The uninsured rate among those ages 26 to 34 has been declining faster than it has among other age groups, Gallup said.
The uninsured rate among those ages 18 to 25 declined slightly to 23.3 percent. The uninsured rate for this age group has generally been steady since December 2010 when the Affordable Care Act provision allowing young adults ages 18 to 26 to remain on their parents' health insurance plans took effect. Prior to that provision, 18- to 25 year olds were the most likely to lack health insurance among all age groups, Gallup said.
Americans who reported they were insured via Medicaid increased to 7.4 percent from 6.6 percent in the fourth quarter of 2013. This might be due to some states choosing to participate in the Medicaid expansion that allows more working poor to participate as a result of ACA provisions.
Fewer U.S. adults said they get their primary insurance through a current or former employer -- 43.5 percent down from 45.5 percent -- in the fourth quarter of 2013.
The survey has a margin of error of 1 percentage point.