Colorado residents who buy their health insurance themselves will pay 20 percent more on average next year, and, for the first time, residents in 14 counties will have the choice of only one carrier offering plans in their area via the state health insurance exchange.

The increases are the largest in Colorado since the 2014 launch of the Affordable Care Act, also known as Obamacare. In some parts of rural Colorado, premium increases will top 40 percent, according to figures approved Tuesday by the Colorado Division of Insurance. However, tax credits for low-income residents will help blunt the impact of some of those increases, with consumers who currently receive the credits in line to see an average decrease of 11 percent in their premiums.

The finalized numbers confirm the worries that began in June when the steep increases were first proposed. In a speech on the floor of the U.S. Senate on Tuesday, Colorado Sen. Cory Gardner, a Republican, blamed the increases on President Barack Obama’s signature health care law, which led to the creation of the exchanges.

“The people of Colorado can’t afford Obamacare,” Gardner said. “Obamacare can’t keep its promises.”

Marguerite Salazar, Colorado’s insurance commissioner, said the increases are the result of rising health care costs overall. The increases for people who buy their plans on the state’s Obamacare exchange and those who buy insurance off of it will be roughly the same.

““Health care costs are increasing across the country, and those costs push up premiums,” Salazar said in a statement.

But Colorado’s increases in 2017 could be worse than those nationally. An analysis done this summer by the Kaiser Family Foundation looked at potential rate increases in 16 major cities, including Denver, and projected that the average increase of plans in the most popular tier of the Obamacare exchanges would be 9 percent in those cities.

The figures released Tuesday are only for individual health care plans that people buy independently. About 450,000 Coloradans — or 7.7 percent of the state — fall into the category.

At least 51 percent of Coloradans receive health care coverage through their employers. The numbers released Tuesday don’t predict price changes in plans for large employers, which are harder to track. Premiums for small-company plans in the state will increase by about 2 percent, according to the Division of Insurance.

“The small group market seems to be stable, with more carriers participating and modest price increases,” the Colorado Health Institute stated in an analysis published online Tuesday afternoon.

But, the institute concluded, the large increases in the individual market reflect the continued upheaval in that corner of the health insurance industry. Two insurers — UnitedHealthcare and Humana Insurance —- won’t offer plans on the state’s Connect for Health Colorado insurance exchange in 2017. Another, Anthem Blue Cross and Blue Shield, won’t offer preferred provider organization — or PPO — plans. And yet another, Rocky Mountain Health Plans, has shrunk its individual-plan business to just Mesa County.

The changes mean that 92,000 people — roughly one of every five consumers in Colorado’s individual market — will be shopping for a new plan when the open enrollment period begins Nov. 1.

The upheaval strikes particularly hard in rural Colorado. In 14 counties — all in western Colorado — residents will have only a single insurance carrier to choose from on the exchange, although that carrier might offer multiple plans. In 16 counties in southern and eastern Colorado, premium increases overall will average more than 40 percent, according to the Division of Insurance’s figures.

The Division of Insurance is charged with reviewing requests for premium increases filed by insurance companies. The division cannot dictate to the companies what the prices should be but can reject the proposed rates if they are too high or too low.

A health care advocacy group, the Colorado Consumer Health Initiative, criticized the process.

“Because of the lack of transparency in some insurer’s filings,” Adam Fox, the initiative’s director of strategic engagement, said in a statement, “it’s hard to say how or if these significant rate increases have been justified.”