Gas prices rose by an average 12.31 cents a gallon nationwide over the past two weeks, reflecting higher crude oil prices, but the rate of increase is slowing, according to a survey. The national average for a gallon of regular gasoline rose to $3.8148 as of March 9, according to the Lundberg Survey of gasoline retailers in the continental United States. Drivers in Denver saw the lowest pump price at $3.36 per gallon, compared with $4.35 in Los Angeles, the nation\'s highest. The national average price jumped 18.6 cents in the previous survey. \"There are reasons to believe the rate of increase may slow again,\" survey editor Trilby Lundberg told Reuters. \"If crude does not jump again immediately, then the gasoline market will be able to peak soon.\" U.S. crude oil prices hit a recent high near $110 a barrel March 1 and have since slipped about $3 to close on Friday at $107.40. Crude prices are up more than 8 percent so far this year, largely due to market fears that efforts to curb Iran\'s nuclear program could spark a military confrontation in the Middle East. Absent an increase in those tensions, gasoline prices in the United States are likely to turn lower in the coming weeks, partly because of relatively soft consumer demand and increased supply on the West Coast, where refineries are returning to operation from seasonal maintenance.