WASHINGTON (AP) — An extensive new survey says the share of Americans without health insurance dropped to its lowest level in seven years in 2014 as President Barack Obama's overhaul took full effect.

Released Tuesday, the Gallup-Healthways Well-Being Index finds a drop of 3.5 percentage points in the share of Americans without health insurance, in a full-year comparison between 2013 and 2014. Research director Dan Witters says about 12.3 million fewer adults were uninsured in the fourth quarter of 2014, compared to the third quarter of 2013.

The trend appears likely to continue, since 55 percent of the remaining uninsured say they plan to get coverage rather than face escalating tax penalties. But first, the Supreme Court must decide if millions of people can continue to receive subsidized coverage.