PROVIDENCE — More than 11,300 people signed up for private coverage through the state’s new health insurance marketplace through December, meaning Rhode Island is well on its way to meeting a March 31 federal enrollment target.The preliminary enrollment data released this week by HealthSource RI are for the period starting Oct. 1, when the marketplace opened for business, to Dec. 31.Like many states, Rhode Island hasn’t publicly released enrollment targets for its marketplace, which is a part of the federal health care overhaul. But the U.S. Centers for Medicaid and Medicare Services set a goal of 5,640 sign-ups in the state by Dec. 31 and 12,000 by March 31, the end of the first open enrollment period.HealthSource RI Director Christine Ferguson has said previously she expects 70,000 to 100,000 people to use the marketplace through the end of this year. More than 120,000 people in Rhode Island are uninsured in a population of just over 1 million. Many are eligible for coverage under Medicaid.State health officials reported last month that 5,280 had newly enrolled in Medicaid in October and November. No updated figures have been released.The state deadline to enroll through HealthSource RI for individual private-plan coverage beginning Jan. 1 was last week. Spokeswoman Dara Chadwick said the payment deadline had been extended to this afternoon.Individuals who want coverage beginning Feb. 1 must enroll and pay the first month’s premium by Jan. 23. Small businesses can enroll at their regular renewal date.The vast majority of Americans are required to have insurance as of this month under the federal law, or face fines. But there is a grace period so anyone who signs up before March 31 won’t be assessed a penalty.One issue on tap for the General Assembly session opening Tuesday in Rhode Island is how to pay for the marketplace down the line. The state has gotten more than $80 million in federal grants to build, launch and operate it, but the federal government is requiring the exchanges to be self-sufficient beginning in 2015.Ferguson previously told lawmakers it would cost $17.9 million to $23.9 million annually for the state to operate HealthSource RI.