A national survey shows gas prices have dropped 15 cents a gallon in the last two weeks. Triple a reports the national average is 3.68 a gallon. California drivers are paying $3.96, while in the grand canyon state its hovering around 3.66 a gallon Despite the drop, gas nationally is almost a dollar higher than a year ago. Prices so far this summer peaked july 11 at $4.11 for a gallon of regular.