California ? People who buy their own health insurance are being asked to pay 20 percent more for the same coverage, according to the Kaiser Family Foundation, but the study provided little data on what’s behind the higher premiums.

In a study released Monday, the foundation found that about three-fourths of the country’s 14 million people who don’t get group coverage said they faced premium increases.

Most paid the increase, perhaps trapped by the inability to find other coverage because of pre-existing conditions, researchers said. Those who switched plans, about 16 percent, “bought down” into plans that provide less comprehensive coverage.

The average premium for an individual policy was about $3,606 annually — less than the $4,824 average premium for those with group coverage. But those on the individual market typically have fewer benefits.