The rates for health insurance plans on Arizona's federal run exchange are fifth lowest in the country and are running below the national average, a federal report said Thursday.

Under the Affordable Care Act, the Arizona insurance marketplace has eight insurers and will offer more than 100 health plans, according to new data from the U.S. Department of Health and Human Services.

The health plans are offered in four categories that have tiered pricing, and the data show Arizona has some of the lowest premiums for health plans available on the exchanges.

“There’s obviously a lot of competition," said Kathleen Oestreich, CEO of Meritus, a nonp[rofit health insurance cooperative. "Some of the markets only have one or two or three competitors. When you have eight, that creates a competition that’s going to make insurers think about their price points."

Oestreich said another factor keeping the state's rates low may be that insurance companies price to what the current uninsured population can afford.

The average of lowest cost plans in Arizona range from $214 to $252, the federal data showed.

People can begin enrollment for plans on the online marketplaces starting Tuesday.