Providing the most detail yet on those who have bought insurance through the federal and state health exchanges, Obama Administration officials say they are still confident that enough young people will sign up for coverage to provide a good mix for health insurers.

"Through December, 30 percent of those who enrolled were under age 35, with 24 percent being between the ages of 18 and 34," said Health Secretary Kathleen Sebelius.

That is still lower than the original goal of the White House, which was to have 35-40 percent of enrollees be from the 18-34 age range - and critics pounded on those numbers.

"If not enough young and healthy people sign up, as is currently the case, taxpayers will have to pay even more," said Sen. Marco Rubio (R-FL), noting that 33 percent of those who have signed up so far are between 55-64 years old.

"These enrollment numbers show that neither enough total people nor enough young people are signing up for ObamaCare, and it’s increasing the risk to taxpayers of bailing out health insurance companies," Rubio added.

When you dig into the numbers, there are some states that look good in terms of the age breakdown - and others where the mix isn't so good.

Only Massachusetts and Washington, D.C. are above the 30 percent mark when it comes to the 18-34 age group, considered to be key to stable and affordable premiums.

At the other end of the scale, five states had 40 percent or more of their enrollments from those who are over 55 years old - Wisconsin, West Virginia, Maine, Ohio and Arkansas.

The feds also provided data on how many people in the exchanges are receiving financial aid from the government to buy health insurance - and the numbers there are overwhelmingly weighted on the side of getting aid.

For example in California - which has signed up almost a half million people - 85% of those private insurance enrollment policies will have the feds chipping in money to pay for coverage.

The average is 79% getting financial aid.

Here is a rundown of some of the statistics - first the total number of people signed up for private insurance (this figure does not include Medicaid or other enrollment.)

That is followed by the percentage of signups between 18-34 years old and then 55-64; there are also figures for the percentages of those getting aid and not getting financial help from the government to buy insurance (some states did not provide those details.)

Providing the most detail yet on those who have bought insurance through the federal and state health exchanges, Obama Administration officials say they are still confident that enough young people will sign up for coverage to provide a good mix for health insurers. "Through December, 30 percent of those who ...