On Friday I wrote about young adult enrollment under the Affordable Care Act, looking at Humana's lower-than-expected sign-up rate and the District's really robust levels of enrollment in that demographic.

Some readers made the case that the District wasn't a good test case, given that Hill staff, who hover around an average age of 31, are largely required to purchase insurance through the DC HealthLink. That's a fair enough point, and a helpful reader points out that Colorado has done excellent record keeping on the age of its enrollees. It might make a better bellwether for how things are going when it comes to reaching those under 35. What you see, in the graph below, is young-adult enrollment well below target levels -- but also increasing over time.

Colorado exchange enrollment, by age (October-December) | Infographics

During the first two months of open enrollment, 17 percent of those signing up for coverage were under 35. In early December, that rose to 20 percent and, for the last two weeks of that month, just about a quarter of those enrolling were in the much-coveted young adult demographic.

You can spin this is bad news: 24 percent of enrollment under 35 is still well below the target of having 40 percent of enrollees be young adults. But, you can spin this as good news, too: Young people have steadily grown as a share of enrollment, much like what happened during Massachusetts' first year of reform.

Most accurately though, this is probably too-soon-to-tell-what's-happening news. This is, alas, the least satisfying type of news, but we still have more than two months of open enrollment left. We also don't have a ton of information; Colorado's detailed record keeping is the exception, rather than the norm. Which means we're probably well into April before we have a great sense of the age mix in this year's enrollment.