Though it began with a rocky start, healthcare signups through the United States' new insurance marketplaces surged this month, bringing total enrollments to 2.1 million for the end of the year. Most notably, enrollment doubled through Healthcare.gov as the deadline for January coverage approached. Given Healthcare.gov's often-inoperable state during the prior months, that statistic isn't necessarily so impressive, but the government is encourage that enrollments will actually continue to grow from now through March, when the enrollment period ends.

December enrollments were nearly six times October and November combined

The improvements on Healthcare.gov appear to have made a dramatic difference though. While it isn't the only way to sign up, the total enrollment for December — for state and federal marketplaces together — was nearly six times greater than the combined number for the prior two months.

"January 1st marks not only the beginning of a New Year, but an exciting new day in health care as millions of Americans will now be able to access care," Health and Human Services secretary Kathleen Sebelius writes in blog post today. Sebelius also notes that HHS is working to ensure that all Americans who want to sign up for coverage through the marketplace will be able to — a reminder that kinks still need to be worked out from its troubled website.

But despite the spike in the insurance marketplaces' enrollments, Reuters reports that they've still fallen short of the administration's hopes. It was reportedly looking for 3.3 million by the end of the year, though it certainly could have done much worse if Healthcare.gov hadn't improved: after its first month, fewer than 27,000 people had managed to sign up through the website. The website is now said to be working for at least 80 percent of users — a number that the administration hopes will continue to quickly rise.