The decline in national average gasoline prices driven by falling oil prices continued unabated with a 5.8-cent decline to $1.856 for the week ending Jan. 25, according to federal data.

Gasoline is now 18.8 cents lower than a year ago, and declined in nine regions tracked by the U.S. Energy Information Administration. The Midwest saw the sharpest decline, falling 8.2 cents to $1.63, while the West Coast and West Coast without California fell 6.4 cents to $2.459 and 5.7 cents to $2.141 respectively. Gasoline is cheaper than a year ago in all regions except the West Coast.

California ($2.668) and Hawaii ($2.631) offer the nation's most expensive gasoline and nine other states plus the District of Columbia have average prices of at least $2 per gallon. And 19 states now have gasoline under $1.75 per gallon. Oklahoma's $1.533 average is the nation's lowest.

Meanwhile, the average price of a gallon of diesel fell 4.1 cents to $2.071. Diesel is now 79.5 cents lower than it was a year ago.