The average U.S. price of regular-grade gasoline remained steady at $2.53 per gallon over the past two weeks. Industry analyst Trilby Lundberg of the Lundberg Survey said Sunday that the price at the pump averages 9 cents higher than it was a year ago. The highest average price in the nation for regular-grade gas is $3.54 per gallon in San Diego. The lowest average is $2.06 in Jackson, Mississippi. The average price of diesel is $2.98, down three cents.