The average price of on-highway diesel fuel declined 1.5 cents, settling to $2.564 per gallon at the pump. The price is still 46.5 cents more higher than it was in the same week of 2016.Prices were down in all major regions of the U.S. with the largest drop coming to the West Coast at 3.1 cents. The smallest change occurred in the Rocky Mountain region with a 0.8-cent drop. Gasoline prices were also down last week, falling 1.8 cents to $2.323 per gallon at the pump. The price of gasoline is 36.2 cents more expensive than it was in the same week a year ago.Pr ices varied by region with the largest decrease in prices hitting the Midwest at 5 cents per gallon. The area with the largest increase was the West Coast where prices jumped 1.9 cents for the week.