The average price of a gallon of gasoline in the United States fell 9 cents in the past two weeks as refiners and retailers reduced their profit margins to sell more fuel, according to a Lundberg survey released on Sunday. Regular grade gasoline fell to $2.35 per gallon in the Sept. 25 survey from $2.44 on Sept. 11, when the previous survey was taken. It has tumbled 36 cents over the past five weeks to the lowest level since late February. Compared with one year ago, the $2.35 average price was $1.03 a gallon lower. The latest decline came despite crude oil prices having strengthened in the last five weeks, survey publisher Trilby Lundberg said. “The main reason for this is that both refiners and retailers have reduced their own profit margins […]