The average price of diesel fuel continued to climb last week as a rebound in the crude oil market put upward pressure on energy costs, according to the latest numbers from the Energy Department.

The price of on-highway diesel fuel rose 7.8 cents last week, increasing the price to $2.099 per gallon for the week. Despite the increases, the price is still 81.8 cents cheaper than it was a year ago.

The largest increase in prices was in the Lower Atlantic region, which saw a 9.1-cent jump for the week. The smallest change was a 5.7-cent increase in New England.

The average price of regular gasoline saw an even more significant increase last week, with prices rising by 12 cents, hitting $1.961 per gallon. The price is 49.2 cents cheaper than it was in the same week last year.

The largest increase was a 15-cent bump on the West Coast, which is also the leader in average gas prices a 2.394 per gallon. The smallest change was an 8.3-cent increase in the Rocky Mountain region.

Last week’s fuel prices coincided with a rally in crude oil prices that has occurred over the past few weeks. However, the trend reversed course today, according to a recent Wall Street Journal report. Analysts had been holding out hope that oil-producing countries would reduce or freeze output at current levels in order to curb the effect of an oil supply glut.

However, over the weekend, Iran declared that it would not participate in the production freeze, opting instead to aim for a target output of 4 million barrels a day. Not only does this potentially increase the global oil supply in a time of weaker demand, but other oil-producing countries may follow suit.