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(CNN) -- Gas prices have fallen by nearly a dime over the past few weeks following the decline in crude oil prices, according to a survey published Sunday.

The average price of a gallon of regular gasoline is $3.61, down nine cents from three weeks earlier, according to the Lundberg Survey.

If crude oil stays at its current level, prices could fall by as much as another 10 cents in the coming weeks, publisher Trilby Lundberg said. But she cautioned, "It's impossible to know what crude oil prices will do next."

The current gas price is nearly 84 cents higher than the price a year ago, Lundberg said.

In addition to crude oil, "We also have declining demand in the U.S. due to our economy," she said. Unemployment and underemployment keep people at home, shrinking gasoline demand.

The Lundberg Survey tabulates prices at thousands of gas stations nationwide.

The lowest average price found in the latest survey, conducted Friday, was $3.26 in Tucson, Arizona. The city with the highest average was Chicago at $3.97.

Here are prices in some other cities:

St. Louis -- $3.29

Jackson, Mississippi -- $3.43

Houston -- $3.49

Salt Lake City -- $3.51

Atlanta -- $3.61

Los Angeles -- $3.70

Boston -- $3.77