ATLANTA (CNN) - Gas prices declined an average of 3.5 cents in the last three weeks, following a typical January trend fueled by decreased demand, the publisher of a national survey said Sunday.

The national average for a gallon of self-service, regular unleaded gasoline dropped to $1.79 between Dec. 17, 2004, and the latest survey, conducted Friday, according to the Lundberg Survey of about 7,000 gas stations nationwide.

The average price has fallen nearly 25 cents a gallon since Oct. 22, the survey found. But it's still 24 cents higher than it was a year ago.

"Drops of this magnitude, if any, are not very likely going forward because gasoline demand will bottom out this month as it always does in January," said survey publisher Trilby Lundberg.

Many refineries take advantage of this slowdown to prepare for the heavy spring and summer driving seasons, taking some capacity off-line to perform routine maintenance and improvements, Lundberg said.

Norfolk, Va., had the lowest price in the nation Friday at $1.65 a gallon. Honolulu had the highest price, $2.32.

Average prices of a gallon of self-serve regular in other cities: Los Angeles -- $1.92; Chicago -- $1.88; Boise, Idaho -- $1.88; Boston -- $1.83; Seattle -- $1.80; Detroit --$1.78; Wichita; --$1.78; Portland, Ore. -- $1.73; Atlanta -- $1.69; Denver -- $1.68; Dallas -- $1.67.