You're not imagining things if it seems like you're paying more for health insurance than ever before.

Health insurance rates for employer-sponsored coverage more than doubled in the last decade, according to the Kaiser Family Foundation, and last year 77 percent of people who bought their own health insurance saw premiums go up, with an average hike of 20 percent.

States are largely in charge of regulating health insurance rates, but their vigilance varies, according to a recent report by the Government Accountability Office (GAO). The GAO surveyed state regulators about how they dealt with health plan rate review in 2010 and how they're using federal grants to boost oversight. The Affordable Care Act included $250 million in grants for states to beef up their review processes, and so far the U.S. Department of Health and Human Services has awarded $46 million to 45 states and the District of Columbia.

Here are five findings that might surprise you:

1. Not all states have the power to prevent outrageous health insurance rate hikes.

According to the GAO report, 28 states last year had "prior approval authority," which means they could approve, change or reject rate increase requests from insurers. But not all of those states had the authority for all types of health insurance. Some had prior approval authority over only individual health plans, but not over group policies, for instance.

2. Not all health insurance rates were reviewed.

Some states didn't review rate filings for group insurance. Illinois and Louisiana, which didn't have the power to approve rates before they went into effect, did not review any rate filings last year.

3. Most rate reviews did not result in lower rates.

Only five states said their reviews led to lower rates than what the health insurance companies proposed originally. They were New York, Utah, Connecticut, North Dakota and Iowa.

Thirteen states reported less than 10 percent of rate reviews resulted in lower rates: Hawaii, North Carolina, New Jersey, Kentucky, Nevada, Texas, South Carolina, Florida, California, Georgia, Washington, Michigan and Maine.

And six states said none of the reviews led to lower rates: Arizona, Idaho, Missouri, Nebraska, Wisconsin, and Wyoming.

4. Consumers don't have a voice in most states.

Consumers had the opportunity to chime in during rate reviews in only 14 states: California, Connecticut, Iowa, Maine, Michigan, New Mexico, New York, Oregon, Pennsylvania, Rhode Island, Texas, Washington, West Virginia and Wisconsin.

5. Some states considered more information than others.

Some states reported doing only cursory reviews, while others, such as Texas, said they did comprehensive reviews. Most states looked at why carriers wanted to change rates and their rate histories and reasons for rate changes, but less than half reviewed carrier reserves and carrier capital levels compared to state minimum requirements.

The good news for consumers: Using federal grant money, states took significant steps last year to strengthen their rate review processes. More than two-thirds reported hiring or contracting with actuaries or improving technology to boost oversight, and more than a third pushed for legislation to give them more authority over health insurance premiums.