(CNN) -- Prices at the pump fell 23 cents per gallon in the United States in the past two weeks, according to a survey released Sunday.The average price of a gallon of self-serve regular was $2.43, the Lundberg Survey found.That was about 20 cents lower than it had been a few days before Hurricane Katrina hit the Gulf Coast on August 29.It was also 41 cents higher than the average a year ago.The survey of gas stations in all 50 states was carried out Friday.Publisher Trilby Lundberg said prices have tumbled as refining capacity has been restored following hurricanes in the Gulf of Mexico region. Also, imports have increased, while demand has dropped.Americans traditionally drive less as fall sets in. And the historically high prices have reduced demand, Lundberg said.A survey two weeks ago found the price had fallen 25 cents during the previous two weeks.Lundberg said Sunday she expects "more price cuts, but at a much smaller rate than we've seen for the past month," as more refining facilities are repaired and the lower prices encourage some people to drive more.The lowest average price the survey found was in Tulsa, Oklahoma, where drivers paid an average of $2.06 for a gallon of self-serve regular. The highest average price was in Miami, at $2.74.Here are some other average prices for a gallon of self-serve regular:San Francisco, California: $2.64Honolulu, Hawaii $2.72Anchorage, Alaska: $2.53Chicago, Illinois: $2.52Denver, Colorado: $2.40Philadelphia, Pennsylvania: $2.38Atlanta, Georgia: $2.35Detroit, Michigan: $2.23Omaha, Nebraska: $2.17