The waiting room at Mary's Center in Washington, DC on February 24, 2014. Mary's Center is a non-profit health center for the underserved, uninsured or underinsured. Linda Davidson | The Washington Post | Getty Images

The rate of Americans with health insurance didn't improve last year for the first time since the Affordable Care Act was passed in 2010. In 2017, 29.3 million people, or 9.1 percent of the population, were uninsured, according to estimates from the Centers for Disease Control and Prevention's National Health Interview. That's up slightly from 28.6 million people, or 9 percent, who didn't have health insurance in 2016. The increase is not statistically significant given the margin of error, though. The figures are still well below the 48.6 million people, or 16 percent of the population, without health insurance when the Affordable Care Act was passed in 2010. However, this could be the beginning of a reversal as Republicans claw away at the landmark health law.

Congressional Republicans tried and failed to repeal Obamacare multiple times last year. They did manage to repeal the individual mandate, which required most people to have some form of health insurance or pay a tax penalty, as part of the broader tax law it passed in December. Experts widely anticipate that the change, which is scheduled to take effect in 2019, will leave more people without health insurance. They also expect premiums in Obamacare exchanges to skyrocket as healthier, younger people choose to forgo coverage.

Josh Peck, co-founder of Get America covered and former chief marketing officer for HealthCare.gov, said he wasn't expecting any dramatic changes this year but expects the conversation to continue next year. "Health care is a little bit like a battleship in that it moves slowly," Peck said. "It takes time for people to get covered ... These policy changes take a little while to show up. It might affect consumers, the marketplace, then it needs to show up in the survey data, and the timeline really does add up." Last year, the percentage of uninsured adults between the ages of 25 and 34 increased to 17.2, up from 16.5 in 2016. This group was almost twice as likely to not have health insurance as adults between the ages of 45 and 65. The percentage of uninsured people in that group also increased. Last year, 9.3 percent of adults between the ages of 45 and 65 were uninsured, up from 8.9 percent in 2016. At the time of the interview, 9.9 million people, or 3.7 percent, obtained health coverage through the Affordable Care Act marketplaces or state-based exchanges. In the fourth quarter of 2017, 9.8 million people, or 3.6 percent, under 65 were enrolled in exchange plans. That's down from 11.6 million people, or 4.3 percent, in the same period in 2016. The number is not statistically significant.