The price of diesel fuel in the U.S. increased again last week, capping off a rally in fuel prices that began more than a month ago, according to the latest numbers from the Energy Department.

The average price of on-highway diesel fuel jumped 4.6 cents last week, hitting $2.586 per gallon at the pump. As the streak of price increases continues, diesel fuel is now 37.5 cents more expensive than it was in the same week of the previous year.

Prices increased in all major regions of the country with the largest spike hitting the Central Atlantic at 8.9 cents per gallon. The smallest amount of change was a 1.9-cent increase in the Rocky Mountain region.

The price of regular gasoline was also up last week, increasing 6.8 cents to an average of $2.377 per gallon at the pump. Regular gasoline is now nearly 35 cents more expensive than it was in the final week of 2015.

The largest increase in gas prices was in the Central Atlantic region with an 8-cent per gallon increase. The smallest increase was on the West Coast where prices still jumped 5.9 cents for the week.

Crude oil prices were down to two-week lows to start 2017 amid new concerns that oil producing countries might not stick to an agreement to freeze oil production, according to a MarketWatch report.

The anxiety is partly caused by the New Year, as new, lower oil production targets were set to kick in on Jan. 1. Until analysts are sure that oil producing countries involved in the deal will abide by the new quotas, the oil market could remain subdued. Prices were also negatively affected by a stronger dollar and a report showing that Libya may be increasing oil production.