WASHINGTON, D.C. --- The U.S. average retail price for regular gasoline Dec. 11 fell 0.4 cent to $2.293 per gallon. Prices were 10.8 cents per gallon higher than at this time last year, according to the Energy Department's weekly survey by the Energy Information Administration (EIA). East Coast gasoline prices rose 1.0 cent to $2.303 per gallon. In the Midwest, prices fell 3.7 cents to $2.224 per gallon. Gulf Coast prices climbed 1.6 cents to $2.198 per gallon. Rocky Mountain prices remained at $2.248 per gallon. The West Coast saw an increase of 1.1 cents to $2.496 per gallon. California prices increased by 0.8 cent to $2.504 per gallon, the EIA reported. Retail diesel fuel prices continued their rise this week, with average nationwide prices increasing 0.3 cent to $2.621 per gallon. That's 18.5 cents more than at this time last year. Regionally, East Coast diesel prices were unchanged at $2.61 cents per gallon. The Midwest price fell 1.5 cents to $2.563 per gallon. The Gulf Coast saw the average diesel price go up 0.3 cent to $2.54 per gallon. Rocky Mountain diesel prices rose 1.7 cents to $2.724 per gallon. Diesel prices on the West Coast increased 7.1 cents to $2.931 per gallon, while prices in California were up 10.3 cents to $2.963 per gallon. California prices were 49.8 cents per gallon higher than at this time last year, the EIA reported.