The national average price of unleaded gasoline fell 1.6 cents to $2.037 for the week ending Dec. 14, according to federal data.

Gasoline is now 51.7 cents lower than it was a year ago and again declined in most regions across the nation as tracked by the U.S. Energy Information Administration. The only increase came in the Midwest, where gasoline moved 1.1 cents higher to $1.901. Four regions now have gasoline costing less than $2 per gallon, including the Lower Atlantic ($1.958), Gulf Coast ($1.788), and Rocky Mountain ($1.995) areas. The sharpest weekly decline came in New England, where the average price fell 4 cents to $2.095.

Among states, only Hawaii ($2.748) and California ($2.651) have gasoline averaging more than $2 per gallon. On the flip side, 26 states have gasoline prices below $2 per gallon. South Carolina's $1.788 is the nation's lowest, according to the AAA's Daily Fuel Gauge Report.

Meanwhile, the average price of diesel fuel fell 4.1 cents to $2.338 for the week. Diesel is now $1.081 lower than it was a year ago.