MEGAN MCARDLE: ObamaCare’s Missing Numbers.

The number 3.3 million represents people enrolled in a policy, not the number who have paid for their premiums. Most of the reporting — which comes from insurance industry sources — suggests that about 80 percent of those who signed up have actually paid the first month’s premium. That would put actual enrollees at more like 2.64 million. The administration now seems unlikely to hit the Congressional Budget Office’s projection of 6 million total enrolled (and paid). If enrollment and payment continue at January’s pace, they will end up under 4.8 million. That’s not necessarily the most likely outcome: We could see a surge in March, like the one we got in December. But it’s a real danger.

The demographic mix isn’t improving as hoped. In order to maintain an actuarially sound pool, and keep premiums down, the exchanges were supposed to have 40 percent of their customers between the ages of 18-34. The demographics slightly improved in January, but young adults still make up only 25 percent of the market.

A lot of people are getting subsidies — as expected. About 80 percent of the folks who bought policies on the exchange so far were eligible for subsidies. That seems high, but it’s roughly in line with estimates from the CBO, which showed six out of seven enrollees getting at least some subsidy from the federal government.

We still have no idea how many of these people previously had insurance. If the administration knows, it is not sharing those numbers with anyone else.

I think if the numbers were good, they’d be sharing.