Diesel and gasoline prices fell for the ninth straight week, bringing diesel prices to their lowest so far for 2012 and gasoline prices to their lowest since February. Oil prices fell again this week due to skepticism about Europe's debt crisis.

Diesel prices dropped 6.5 cents this week to $3.781 per gallon, according to a weekly report from the U.S. Department of Energy. California saw the biggest regional decrease, with prices dropping 12 cents to $3.902. Diesel prices are down more than 17 cents from a year ago.

U.S. gasoline prices also fell this week, by an average of 4 cents to $3.572. The West Coast had the biggest decrease with a drop of 9.2 cents to $4.093. Currently, the Gulf Coast is the region with the lowest gasoline prices, an average of $3.311.

Despite a boost for Spain's economy in the form of a $125 billion bailout loan for its banking system, analysts are still skeptical about the debt crisis in Europe. That skepticism caused oil prices to fall this week. Benchmark oil fell $1.40 to $82.70 per barrel in New York. Brent crude settled at 81 cents to $98.66 per barrel in London.

Spain is the fourth European country to request financial help since the start of the debt crisis, after Greece, Portugal and Ireland.