The average price of diesel dropped by half a cent this week to $4.142 per gallon, ending a nine-week trend of price increases. Despite the decline, the price of diesel is still an average of 16.6 cents higher than this time last year, according to the Energy Information Administration's weekly fuel update.

Prices increased by 0.1 cent in the Central Atlantic region, the only region that saw an increase. California saw the biggest decrease, though it was only by 2 cents, not enough to keep the state from having the highest average diesel price in the country at $4.456.

Gas prices continued their upward trek with a 2.3-cent increase to $3.941 a gallon. This is the 10th straight week of rising gas prices. Only the West Coast saw some relief with a price drop of 1.1 cents.

Oil prices increased by the most in six weeks. Light sweet crude oil futures for May delivery gained $2.21, or 2.2%, to close at $105.23 a barrel on the New York Mercantile Exchange. Brent crude climbed $2.55 to $125.43 a barrel.

Rising oil prices increased discussions about the possibility of opening the national Strategic Petroleum Reserve, a reserve the president can allow access to in response to emergencies and disruptions of oil supplies, reports Reuters. Currently, the SPR holds 800 million barrels of oil.

Companies that receive SPR oil must return equal amounts after prices have lowered or the emergency dies down.

Last June, the reserves were tapped after civil war in Libya. The U.S. sold 30 million barrels to 15 companies to fill the 2-million-barrel-a-day-loss from Libya. Other events during which oil was released include Hurricane Katrina in 2005 and Operation Desert Storm in 1991.