ObamaCare faces a tougher path ahead in enrolling the roughly 30 million people who remain uninsured, despite the record gains already made. The administration signed up 12.7 million people for coverage in 2016, a significant number, but only a small bump from the 11.7 million enrolled last year. Officials warned from the start that this year would be the hardest yet, because the people most eager to sign up already had. The health law has already made major gains, expanding coverage to 16.3 million people and lowering the uninsured rate to a record low of 9 percent, according to a survey last year from the Centers for Disease Control and Prevention.