Premiums in Georgia’s Affordable Care Act insurance exchange showed only a slight increase in 2015, as compared with the South overall and the nation as a whole, an analysis released Tuesday shows.

The Urban Institute study found that nationally, the average premium increase in the lowest-cost “Silver” plan was 2.9 percent. Silver plans are the most popular among consumers, and the rates studied pertain to a 40-year-old individual who does not use tobacco.

The Georgia increase in the lowest-cost Silver plan was just 1.8 percent in 2015, rising from $255 to $260 a month. The national average for that plan was $264.

The 14-state Southern region climbed 5.4 percent from 2014, the first year for the individual state exchanges, a key element of the ACA’s plan to cut the rolls of uninsured.

Rural areas of Georgia actually saw a decrease in monthly premiums for the lowest-cost Silver plan – from $303 to $289.

The percentage changes in premiums in the study are adjusted, or weighted, by where most of the population lives in a state, region or the country.

Bill Custer, a health insurance expert at Georgia State University, said Tuesday that the biggest factor in Georgia’s relatively modest increase “was the increased competition throughout the state in 2015 relative to 2014, especially in rural areas.’’ .

Last year, only one health insurer, Blue Cross and Blue Shield of Georgia, offered exchange plans statewide. Four have statewide offerings in 2015.

The 2014 insurance exchange featured wide variability in rates among different regions in the state. In metro Atlanta, multiple plan choices were offered, while in southwest Georgia, only Blue Cross offered plans.

The southwest Georgia region had among the highest exchange premiums in the nation last year. The area has little competition among medical providers.

Among the 40 cities analyzed, Atlanta’s lowest-cost Silver premium rose 8.2 percent to $248, but it’s still significantly lower than in rural Georgia. The lowest city in the Southern region was Memphis, at $184, while Charlotte was the highest, at $324.

The state with the lowest Silver premium in the Southern region was Tennessee, at $199, while the highest was in North Carolina, at $307.

The Urban Institute report said many health insurance markets in the South have few competitors, with many dominated by Blue Cross–affiliated plans.

John Holahan of the Urban Institute told Georgia Health News that overall, insurance competition is working effectively within exchanges.

“For most insurers, this [the exchange] is really the only growth market,’’ Holahan said. “Employer coverage has been slowly falling.”

Insurers thus have incentives to compete for market share in the exchange, he added.

And consumers, with prices of various health plans easily comparable on the internet, can more easily search for the cheapest option through better transparency, Holahan said. “It’s a competitive dynamic that’s interesting to watch.”

For half the U.S. population, the lowest-cost insurer changed from 2014 to 2015, meaning that many consumers had to switch plans to get the least expensive option.

But Kathy Hempstead of the Robert Wood Johnson Foundation, which funded the analysis, said that in many cases, “lower premiums were offset by higher cost-sharing for health care services and prescription drugs, so consumers considering switching needed to think about more than premiums.”

And some exchange enrollees have complained about “narrow networks,’’ or a limited selection of hospitals and doctors in health plans.

This story was done in collaboration with Kaiser Health News, an editorially independent program of the Kaiser Family Foundation. Andy Miller is the CEO and editor of Georgia Health News, a news organization covering health care in the state. The GHN website is georgiahealthnews.com.