Diesel prices have ended 2015 with a seventh consecutive weekly decline, falling to the lowest levels this year.The average U.S. retail pump price for diesel was down 4.9 cents in the Dec. 28 report by the Energy Information Administration (EIA), to $2.235 per gallon. The price is about $0.98 per gallon cheaper than this time last year.Prices were down in every region of the country, paced by the West Coast less California where a gallon of diesel dropped 8.1 cents to $2.292. The Rocky Mountain region saw a 7.7 cent decline to $2.227 while the Midwest price was down 6.4 cents to $2.163.New England reported a 3.2 cent drop to $2.365, while the price fell 2.6 cents in the Central Atlantic to $2.412, and fell 4.9 cents in Lower Atlantic region to $2.161.California registered 0.02 cent decline to $2.609, still the highest price in the contiguous 48 states. The Gulf Coast reported a 4.1 cent drop to $2.14, the lowest price for a gallon of diesel in the nation.