The average price of a gallon of unleaded gasoline fell 10.4 cents to $2.299 for the week ending Dec. 29, closing out a year of sharply declining fuel prices that have brought gasoline prices to a 5-year low.

The price of unleaded is now $1.032 lower than it was a year ago, according to federal data. For the week, prices fell in nine regions tracked by the U.S. Energy Information Administration. The Rocky Mountain region led the decline, falling 15.6 cents to $2.228 per gallon. Gulf Coast gasoline remains the cheapest at $2.073 per gallon.

The average gasoline price has fallen below $2.50 per gallon in 38 states. It has fallen below $2 per gallon in Oklahoma ($1.98) and Missouri ($1.934), according to the AAA's Daily Fuel Gauge Report.

Meanwhile, the average price of diesel fuel fell 6.8 cents to $3.213. Diesel costs 69 cents less than it did a year ago.