The national average price of gasoline has increased for 14 days in a row to $2.21 on Dec. 12 after the Organization of Petroleum Exporting Countries (OPEC) agreed to cut oil production, according to AAA.

The average price increased three cents for the week and two cents on the month. It reached a level that's now 20 cents above the same time a year ago.

OPEC plans to reduce output by 1.2 million barrels per day starting in January, which is expected to bring higher prices if all of the countries implement agreed-upon production levels. Iran and Iraq had initially resisted the move.

Average gasoline prices have fallen below $2 per gallon in four states today including Oklahoma ($1.96), Missouri ($1.97), Arkansas ($1.98), and Texas ($1.99).

The largest monthly increases include Michigan (23 cents), Indiana (22 cents), Ohio (21 cents), Illinois (15 cents), Kentucky (13 cents) and Delaware (12 cents).

Prices fell on the West Coast, expect for Hawaii, with the average price for the region falling 1.5 cents to $2.556, according to the U.S. Energy Information Administration. The sharpest increase came in the Midwest, where prices increased 5.5 cents to $2.162.

Meanwhile, the average price of diesel increased 1.3 cents to $2.493. Diesel is now 15.5 cents higher than it was a year ago.