The average domestic round-trip air fare at Dayton International Airport rose 12.4 percent to $370.88 in the second quarter when compared with same period in 2010, putting Dayton 26th among the nation’s top 100 airports for highest air fares, the government said.

The rise at Dayton exceeded the average increase of 8.5 percent across the nation, the Bureau of Transportation Statistics, part of the U.S. Department of Transportation. Fares in the second quarter this year — not adjusted for inflation — were the highest of any quarter dating to at least 1995, the government reported.

Cincinnati/Northern Kentucky International Airport saw an 11.8 percent increase to $425.67. Cincinnati, where Delta Air Lines is dominant, remains one of the nation’s most expensive airports for fares.

The Indianapolis airport had a 16.1 percent increase to $367.62. At Port Columbus International Airport, the increase was 12 percent to $353.18.

Air fares are rising as carriers cut the number of flights they offer in order to save money. Increased fuel costs have prompted the airline industry to fly fewer flights, but with more passengers per plane. The demand for those fewer seats is pushing up prices, industry observers said.

Airports are trying to work with the airlines to retain existing air service during this period, said Terrence G. Slaybaugh, Dayton’s director of aviation who manages Dayton International Airport.

“I don’t think it’s having a big impact yet,” Slaybaugh said. “The market here responds and fills planes up.”

The government defines itinerary fares as round-trip, unless the customer does not buy a return trip.

The reported fare amounts include the price charged by the airline, plus taxes and fees levied by outside entities.