The national average price of unleaded gasoline fell to $2.31 per gallon for the week ending Jan. 23, as U.S. oil production continues to increase, according to AAA.

The average price declined three cents during the week and four cents during the month. It remains 46 cents higher than a year ago. It has fallen 14 of the past 15 days.

The average price fell 3.2 cents to $2.326 per gallon as tracked by the U.S. Energy Information Administration. It was 47 cents higher than a year ago.

The sharpest decline came in the Midwest with a 6.4-cent decrease to $2.219. The West Coast without California was the one region that increased; it moved two-tenths of a cent to $2.492, according to the E.I.A.

The nation’s top five least expensive markets are: South Carolina ($2.07), Tennessee ($2.11), Alabama ($2.11), Mississippi ($2.11) and Indiana ($2.12). The states with the largest weekly decreases in gas prices include: Ohio (13 cents), Michigan (12 cents), Indiana (eight cents), Illinois (eight cents), and Kentucky (six cents).

Meanwhile, the average price of diesel fell 1.6 cents to $2.569 per gallon. Diesel is now 49.8 cents higher than it was a year ago, according to the federal data.