ATLANTA (CNN) - The average price of a gallon of self-serve regular dropped nearly a penny during the past two weeks, to $1.92, continuing a 9-week decline of 15 cents from its all-time high, according to a national survey.

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Not accounting for inflation, gas prices hit an historic high on May 21 at $2.07, said Trilby Lundberg, publisher of the Lundberg Survey, which tallies gas prices at about 7,000 service stations nationwide.

The survey date was July 23.

Lundberg said the drop resulted from completion of routine maintenance and repair at the nation's refineries. Those repairs had forced the refineries off-line, limiting supply and boosting prices ahead of the peak U.S. driving season, which has just begun.

"The capacity came back and is now sufficient to supply our summer gasoline demand," she said.

Given the pledge of some OPEC countries to continue to boost output, prices will continue to dip slightly in the coming weeks, Lundberg predicted.

Drivers in Tulsa, Okla., paid the least, at $1.74 per gallon; drivers in Honolulu paid the most, at $2.25.

Other prices around the nation include: Denver, $1.87; Wichita, Kan., $1.89; Portland, Maine: $1.92; Reno, Nev., $2.07; Long Island, N.Y., $2.15; Los Angeles, $2.14; Atlanta, $1.82.