Prices for the average plan under the Affordable Care Act have been taking off lately, and this year is no different.

Linda J. Blumberg, John Holahan, and Erik Wengle at the Robert Woods Johnson Foundation and Urban Institute, decided to find out just how much prices were increasing and why.

First off, the researchers said that using a national aggregate in order to gain an understanding of how and why premium prices are increasing doesn't make much sense due to the variance of the exchanges where the insurance plans are offered.

"We conclude that a national average rate of premium increase is a fairly meaningless statistic since different markets are having very different experiences," said the report.

"The focus of attention should be on understanding the wide variability by identifying the characteristics of markets that have experienced high premiums or high growth in premiums and of markets with lower premiums or lower growth in premiums."

Only five states saw a decrease in premium cost this year, while 12 states had increases of more than 20%, on average. The heavily impacted states are predominately in the Midwest, but almost every region got hit with price jumps.

The variance is startling. The largest increase came from Alaska, which saw premium prices surge 40.2% this year, while on the other end, Indiana's prices decreased by 12.1%.

In all, about 48% of the population lives in areas where prices decreased or increased by less than 5%. 26.3% of the US population lives in areas that had an increase of more than 15%.

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The researchers found that there are a variety of reasons for the discrepancy in prices, but the biggest difference-maker was competition.

"However, the most important factors associated with lowest-cost silver plan premiums and premium increases are those defining the contours of competition in the market," the report concluded. "Rating areas with more competitors had significantly lower premiums and lower rates of increase than those that did not."

The paper also found that there was one player that had more of an effect on prices than any other provider.

"Those rating areas with a Medicaid insurer competing in the marketplace also have lower premiums and lower rates of increase than those regions without a Medicaid insurer competing," said Blumberg, Holahan, and Wengle.

This is an issue as insurance companies evaluate the profitability of the state exchanges. With political pushback against expanding Medicaid considerable, private insurers are going to have to carry most of the load and provide competitions.

The nation's largest insurer, United Healthcare, has already dropped out, leaving more (though not significantly more) Americans with one or two choices. If other insurers were to take a similar tact, though unlikely, it could cause an even further increase in prices.

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6 PHOTOS SCOTUS hears Obamacare contraceptives challenge See Gallery Here's how much the price of Obamacare changed this year for every state in the US WASHINGTON, DC - MARCH 23: Nuns supporting Little Sisters of the Poor, attend a rally in front of the US Supreme Court, March 23, 2016 in Washington, DC. Today the high court will hear arguments in Little Sisters v. Burwell, which will examine whether the governments new health care regulation will require the Little Sisters to change their healthcare plan, to other services that violate Catholic teaching. (Photo by Mark Wilson/Getty Images) WASHINGTON, DC - MARCH 23: Nuns supporting Little Sisters of the Poor, attend a rally in front of the US Supreme Court, March 23, 2016 in Washington, DC. Today the high court will hear arguments in Little Sisters v. Burwell, which will examine whether the governments new health care regulation will require the Little Sisters to change their healthcare plan, to other services that violate Catholic teaching. (Photo by Mark Wilson/Getty Images) WASHINGTON, DC - MARCH 23: Nuns supporting Little Sisters of the Poor, attend a rally in front of the US Supreme Court, March 23, 2016 in Washington, DC. Today the high court will hear arguments in Little Sisters v. Burwell, which will examine whether the governments new health care regulation will require the Little Sisters to change their healthcare plan, to other services that violate Catholic teaching. (Photo by Mark Wilson/Getty Images) WASHINGTON, DC - MARCH 23: Nuns supporting Little Sisters of the Poor, attend a rally in front of the US Supreme Court, March 23, 2016 in Washington, DC. Today the high court will hear arguments in Little Sisters v. Burwell, which will examine whether the governments new health care regulation will require the Little Sisters to change their healthcare plan, to other services that violate Catholic teaching. (Photo by Mark Wilson/Getty Images) WASHINGTON, DC - MARCH 23: Nuns supporting Little Sisters of the Poor, attend a rally in front of the US Supreme Court, March 23, 2016 in Washington, DC. Today the high court will hear arguments in Little Sisters v. Burwell, which will examine whether the governments new health care regulation will require the Little Sisters to change their healthcare plan, to other services that violate Catholic teaching. (Photo by Mark Wilson/Getty Images) WASHINGTON, DC - MARCH 23: Nuns supporting Little Sisters of the Poor, attend a rally in front of the US Supreme Court, March 23, 2016 in Washington, DC. Today the high court will hear arguments in Little Sisters v. Burwell, which will examine whether the governments new health care regulation will require the Little Sisters to change their healthcare plan, to other services that violate Catholic teaching. (Photo by Mark Wilson/Getty Images) Up Next See Gallery Discover More Like This HIDE CAPTION SHOW CAPTION of SEE ALL BACK TO SLIDE

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