Supporters of the Affordable Care Act got another data point to add to their arsenal Monday with the release of a new report showing the percentage of Americans without health insurance has seen a significant drop in recent months.

New Gallup data shows that the uninsured rate fell from 18.1% in the third quarter of 2013 to 15.6% in the first quarter of 2014, the period during which Americans were able to sign up for health coverage using federal and state insurance exchanges. The survey conducted through March 31, the final date of open enrollment, found the percentage of Americans without health insurance dropped to its lowest level since before President Barack Obama took office.

The rate with which Americans obtained insurance increased from month to month during the beginning of 2014, dropping from 16.2% in January to 15.0% in March. The uninsured rate dropped from 15.8% in the first half of March to 14.7% in the second half, a sign “that enrollment through the healthcare exchanges increased as the March 31 deadline approached,” according to Gallup’s own analysis.

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The White House waged an aggressive campaign to encourage Americans to sign up for insurance during the enrollment period, ramping it up especially in the final weeks with appeals targeted towards younger groups like an appearance on Funny or Die web show “ Between Two Ferns ” and posting the president’s March Madness brackets on a health-focused part of the White House website. NBA superstar LeBron James even joined the campaign, appearing in an ad encouraging enrollment.

Despite that focus on young Americans, the uninsured rate dropped pretty uniformly across all age groups between the ages of 18 and 65, with about a two-point drop for each group. Seniors, who already enjoy the lowest uninsured rates thanks largely to Medicare, saw a tiny drop as well from 2% to 1.9%.

Americans under 25 saw the biggest drop in health insurance during Obama’s first term in office, when the Affordable Care Act provision allowing parents to continue to insure children under 26. At that point, the 25 and under set saw their insured rates surpass those in the 26 to 35 age range for the first time in years, according to the Gallup data.

Across racial lines African-Americans saw the biggest drop in their uninsured rate, with a 3.3% drop from the fourth quarter of 2013 to the first quarter of 2014. Hispanic Americans saw a smaller drop of only 1.7% over the time period, and continue to be the least likely to have insurance, with an uninsured rate of 37% compared to 17.6% for blacks and 10.7% for whites.

Lower income Americans saw the biggest drop among socioeconomic groups, with rates going from 30.7% to 27.5% in the last few months from those making $36,000 or less per year.