WASHINGTON — The number of uninsured U.S. residents fell by more than 11 million since President Barack Obama signed the health care overhaul five years ago, according to a pair of reports today from the federal Centers for Disease Control and Prevention.

Although that still would leave about 37 million people uninsured, it’s the lowest level measured in more than 15 years.

The most dramatic change took place in comparing 2013 with the first nine months of 2014. As the health care law’s major coverage expansion was taking effect, the number of uninsured people fell by 7.6 million over that time.

That’s “much bigger than can possibly be explained by the economy,” said Larry Levitt of the nonpartisan Kaiser Family Foundation. “The vast majority has to be due to the Affordable Care Act.”

Obama says the law in many ways is “working even better than anticipated.”