The national average price of gasoline fell 4.3 cents to $3.635 per gallon for the week ending July 14, according to the latest data from the U.S. Department of Energy.

The price of a gallon of regular unleaded is now four-tenths of a cent below where it was a year ago. Prices fell in eight of the nine sub-regions tracked by the U.S. Energy Information Administration. The sharpest decline came in the Midwest where the average price fell 7.5 cents to $3.539. Prices rose in the Rocky Mountain region by two-tenths of a cent to $3.644.

The average price is now at least $3.50 in 37 states and the District of Columbia, according to the AAA's Daily Fuel Gauge Report. This is down from 40 states a week ago.

Meanwhile, the average price of diesel fell 1.9 cents to $3.894 per gallon. Diesel fuel now costs 2.7 cents more than it did a year ago.