The number of people who enrolled in Affordable Care Act coverage for 2017 and paid their premiums — rather than just signing up — is 10.3 million, the Centers for Medicare and Medicaid Services announced today. That's down from the 12.2 million people who had signed up for health care plans during the ACA's last open-enrollment period, meaning 1.9 million people didn't follow through by paying their premiums.

Why it happened: A separate CMS survey found that nearly half of all people who canceled their coverage before paying their premiums said they were worried about the cost.

Why it matters: It's likely to add to the debate about how successful the ACA actually is — and whether the Trump administration hurt enrollment by pulling some of the advertising at the end. There's always a drop off when some ACA customers don't pay their premiums, but this year's total is significantly lower than last year's, when 11.1 million people enrolled and paid their premiums.