UPDATED--The price paid at the pump for diesel is down by the biggest margin in five months due to a drop in oil prices.

The average U.S. cost for diesel has declined 2.5 cents over the past week, coming in at $3.949 per gallon, 13.7 cents lower than the same time a year ago, according to a new U.S. Energy Department report. This is the second straight week that the average price has fallen.

It ranges from a low of $3.862 in the Gulf Coast region, down 2.7 cents, to a high of $4.111 in the West Coast region, falling 2.7 cents.

Prices fell in all parts of the country except in the Rocky Mountain region, where it gained 0.2 cents, for an average of $3.943 per gallon. The biggest drop was recorded in the Central Atlantic sub region of the East Cost, losing 2.9 cents, for an average of $4.015.

The average cost of gasoline also declined, dropping 5.2 cents over the past week, to $3.495 per gallon, just over 33 cents less than it was the same time a year ago.

Prices declined in all parts of the country with the average ranging from a low of $3.231 in the Gulf Coast states, down 7 cents from last week, to a high of $3.866 in the West Coast region, a decline of 3.4 cents during the same time.

This comes as the price of oil has been falling since hitting around a two-year settlement high of more than $110 per barrel earlier this month. It lost $1.16 in trading in New York on Monday, closing at $103.59, which is also down nearly $3 from a week earlier, as the risk of U.S. military intervention in Syria wanes over its purported use of chemical weapons.

Update adds gasoline prices.