WASHINGTON, D.C. --- The U.S. average retail price for regular gasoline dropped 10.9 cents last week to hit $2.618 per gallon as of Sept. 11. That's 33.7 cents lower than the price during the same period last year, according to the Energy Department's Energy Information Administration (EIA). Prices fell for the fifth week in a row, reaching the lowest national average price since April 3, 2006. East Coast prices fell 9.9 cents to $2.654 per gallon, while the Midwest saw the largest regional price decrease of 15.0 cents to $2.448 per gallon, the EIA reported. West Coast prices were still the highest in the nation after falling 6.0 cents to $2.906 per gallon, the lowest price in that region since April 17. California prices were 6.1 cents lower at $2.949 per gallon, also the first time the state average has been below the $3 mark since April 17. Retail diesel fuel prices fell by 11.0 cents to reach $2.857 per gallon as of Sept. 11, still 1.0 cent higher than last year. This is the fourth week in a row that diesel prices have fallen. Prices were down throughout the country, with the Midwest seeing the largest regional decrease of 15.0 cents to $2.787 per gallon, the EIA said. The Rocky Mountains region, which retains the highest regional diesel price in the country, saw a decrease of 8.2 cents to $3.236 per gallon. West Coast prices fell 6.20 cents to $3.137 per gallon.