The prices of diesel and gasoline fuel dropped further for the week amid a volatile crude oil market, according to the U.S. Energy Department.

The national average price of a gallon of on-highway diesel fuel dropped 2.4 cents last week to settle at a price of $2.493. The price is down $1.285 per gallon compared to a year ago.

Prices were down across the U.S., when broken down by region, with the largest decrease coming to New England with a 4-cent decrease. The smallest decrease was in California with a 1.5-cent drop.

The national average price of a gallon of regular gasoline was also down last week – dropping 4.8 cents and settling at $2.327 per gallon.  The price is $1.026 per gallon cheaper than this same week last year.

The largest drop in gas prices came to the West Coast region with an 8.1-cent decrease. The smallest decrease in prices occurred in the Midwest region with a 0.9-cent drop.

Crude oil prices were up as much as 3% on Monday as a result of rising concerns that oil production would get too low by the end of the year. For a more in-depth look at the crude oil market check-out our earlier story.