CAMARILLO, Calif.—The average U.S. price of regular-grade gasoline jumped 3 cents over the past three weeks, to $3.25 per gallon. Industry analyst Trilby Lundberg of the Lundberg Survey said Sunday that gas prices could stop climbing now that crude oil costs have started to fall. The price at the pump is a dollar higher than it was a year ago. Nationwide, the highest average price for regular-grade gas is in the San Francisco Bay Area, at $4.50 per gallon. The lowest average is in Baton Rouge, Louisiana, at $2.74 per gallon. According to the survey taken Friday, the average price of diesel was $3.33 a gallon, up 2 cents from three weeks earlier.