More than half a million Georgians signed up for Obamacare plans through the federal insurance marketplace this year — a 70 percent jump from 2014, data shows.

Nationwide, Georgia and other states that refused to expand Medicaid and still have large numbers of uninsured residents experienced larger increases in marketplace enrollment, according to a report by the nonprofit Urban Institute.

Experts say the jump in enrollment reflects pent-up demand for health insurance from millions of Americans, especially in states that have not expanded Medicaid as called for by the Affordable Care Act. Georgia has the second highest uninsured rate in the country, second only to Texas, a recent Gallup survey showed.

Consumer advocates, community leaders, health care providers and others have urged Gov. Nathan Deal to expand Medicaid, the government health program for the poor. Deal and other conservative leaders, however, have remained steadfastly opposed to growing the program, saying Georgia can’t afford it.

“I’m not at all resigned to having the status quo,” said Cindy Zeldin, head of the nonprofit advocacy group Georgians for a Healthy Future. “There was a clear, unmet demand (for health insurance) in Georgia, and it’s clear that we’d benefit from expanding Medicaid.