Diesel fuel prices in the U.S. have plateaued again, changing by less than a cent over the past three weeks, according to the latest numbers from the Energy Department.

The average price of on-highway diesel fuel was up 0.01 cents last week, increasing to $2.479 per gallon at the pump. The average price is nearly equal to where it was in the same week of 2015 and is cheaper by only 0.06 cents.

Prices were up in most regions of the U.S. with the largest increase occurring on the West Coast at 1.9 cents per gallon. Some areas saw a decrease in prices with the largest drop being a 0.9-cent decrease in the Rocky Mountain region.

The price of regular gasoline was down last week, falling 1.3 cents and settling at 2.23 cents per gallon. Compared to prices in the same week of last year, gasoline is 0.06 cents more expensive.

The largest decrease in prices by region was in the Midwest where prices fell 3.2 cents for the week. Prices were up in some areas with the West Coast posting a 1.7-cent increase for the week.

Crude oil prices were at the lowest levels in a month as several non-OPEC member countries declined to adjust production levels to lower global demand, according to a MarketWatch report.

Rumors have abounded about a tentative agreement between members OPEC to freeze production levels and address a supply glut that has kept oil prices at low levels for most of 2016. However, with the prospect of a deal becoming uncertain and non-OPEC countries refusing to participate, prices may hover around $50 per barrel for the foreseeable future.