The American Automobile Association says the national average price of regular gasoline fell below four dollars a gallon. The national average was $3.99 a gallon last week, a sharp drop from the record high of five dollars a gallon in mid-June. Prices havenâ€™t been below four dollars since March. Oil prices worldwide have dropped amid rising concern about the global economy, which has taken gas prices lower as well. Brent, the global benchmark for oil prices, has fallen under $100 per barrel, down from more than $120 in June. NPR says industry analysts expect prices will continue falling but how long that will continue depends on what happens to oil prices in the future. Global economic concerns, especially as food and energy prices climb, will continue to determine the amount of oil demand. Oil producers in the U.S. and around the world worry about overproducing oil given the worldâ€™s economic fears.