WASHINGTON, D.C. --- For the fourth straight week, the U.S. average retail price for regular gasoline dropped last week, falling 6.7 cents to $3.009 per gallon as of June 18. Gasoline prices were 13.8 cents per gallon higher than this time last year, reported the Energy Department's Energy Information Administration (EIA). All regions reported price decreases. East Coast prices dropped 4.6 cents to $2.976 per gallon. The largest regional decrease was in the Midwest, where prices fell 8.9 cents to $2.984 per gallon. Prices for the Gulf Coast decreased 5.9 cents to $2.903 per gallon. Rocky Mountain gasoline prices fell 4.4 cents to $3.181 per gallon but remain 33.8 cents per gallon above last year's price. West Coast prices were down 7.7 cents to $3.188 per gallon. The average price for regular grade in California was down 8.4 cents to $3.236 per gallon, the EIA reported. On the other hand, retail diesel prices rose last week, climbing 1.3 cents to an average of $2.805 per gallon. Diesel prices, however, were 11.0 cents per gallon lower than at this time last year, the EIA reported. East Coast diesel prices were up 1.1 cents to $2.800 per gallon. In the Midwest, diesel prices rose 2.1 cents to $2.774 per gallon. The Gulf Coast saw an increase of 1.1 cents to $2.753 per gallon. The Rocky Mountain region saw the only drop in diesel prices, with prices falling 3.0 cents to $2.907 per gallon. The West Coast average price rose 1.7 cents to $2.958 per gallon. California diesel prices rose 3.6 cents to $3.033 per gallon, but remained 15.2 cents per gallon lower than at this time last year.