RIVERSIDE (CNS) - The average price of a gallon of self-serve regular gasoline in Riverside County today dropped for the 55th time in 56 days, decreasing two-tenths of a cent to $2.666, its lowest amount since Dec. 22, 2016.The average price is 3.5 cents less than one week ago, 34.4 cents lower than one month ago and $1.394 below what it was one year ago, according to figures from the AAA and Oil Price Information Service. It has decreased 84.2 cents since the start of the year, including 1.5 cents on Tuesday.The average price dropped 53 consecutive days, rose six-tenths of a cent on Monday, then resumed decreasing on Tuesday. It has dropped 80 cents over the past 56 days.The 2016 average included stations in San Bernardino County.The dropping prices are the result of a sha