Weekly average on-highway diesel and regular gasoline fuel prices saw significant drops last week, according to the latest numbers from the Energy Department.

The average price of a gallon of diesel fuel dropped by 6.5 cents in a single week, settling to a new low of $2.112. That price is 82.1 cents cheaper than it was a year ago and is a continuation of the downward trend in prices seen throughout 2015.

When broken down by area, the largest drop in prices was in the Midwest at 7.3 cents per gallon while the smallest drop was found in the Central Atlantic region at 4.5 cents.

Gasoline prices saw an even bigger drop with an 8.2-cent drop, falling to 1.914 per gallon. Despite the low prices, the price is only 15.2 cents cheaper than it was in the same week a year ago.

Prices were down across the U.S. last week with the largest drop in prices coming to the Midwest at 10.9 cents per gallon. The smallest price drop was in the Rocky Mountain region at 4 cents even.

Oil prices hit some of the lowest levels of the 21st century on Tuesday as the U.S. lifted its sanctions on Iranian oil, allowing an already oversupplied market to gain another producer, according to a Wall Street Journal report. Oil prices fell over 3% for the day hitting a 12-year low. 

Currently, the cost of oil is trading at around $28 per barrel.