U.S. retail gas prices dropped nearly 22 cents a gallon in the past two weeks, the second decline in a row since a mid-August peak, according to a survey released Sunday.

The national average for self-serve regular stood at about $2.65 on Sept. 8, down from about $2.87, according to the Lundberg Survey of 7,000 gas stations across the country. That was about 35 cents less than last year at this time.

Mid-grade prices averaged $2.77 a gallon, while premium cost $2.87.

Get more high-powered coverage in the Energy Center.

Gas prices peaked Aug. 11 at $3.02 and have fallen nearly 37 cents since.

The lowest gas prices found in the most recent survey was $2.32 a gallon for regular in Des Moines, Iowa, and the highest was in Honolulu at $3.17.

Among California cities surveyed, the highest average price for regular was $2.96 a gallon in Los Angeles. The lowest, $2.83 a gallon, was in Sacramento.

The average for self-serve regular in California was about $2.92, a drop of nearly 15 cents in the past two weeks, the survey found.