Gas prices at AAFES and NEX pumps on bases in Japan and Okinawa will top $4 a gallon for the first time Saturday, three weeks after South Korea and Guam surpassed the mark.

Midgrade unleaded gas in Japan and Okinawa will cost motorists $4.004 a gallon after midnight Friday, a jump of nearly five cents from the previous week, according to the Army and Air Force Exchange Service. Navy Exchange prices follow those set by AAFES.

Regular unleaded gas, meanwhile, continues to climb in South Korea and Guam, where prices Saturday were to rise 5 cents to $4.147 and $4.189 a gallon, respectively.

Premium unleaded also increases slightly, to $4.379 a gallon in South Korea, and $4.419 in Guam.

Diesel fuel, where sold, will remain unchanged across the board: $4.497 per gallon in Japan and Okinawa, and $4.757 in South Korea.

At Marine Corps Air Station Iwakuni, where Marine Corps Community Services controls gasoline sales, the price remains at $3.47 per gallon for unleaded. The price has been unchanged since December.

The record prices at AAFES and NEX pumps mirror stateside trends. The U.S. average retail price for regular gasoline rose for the twelfth consecutive week, up 4.3 cents a gallon to $4.082, according to the U.S. Energy Information Administration.

According to a recent story in The New York Times, Americans on average currently spend about 4 percent of their after-tax income on transportation fuels. That percentage has been higher in the past.

Brian A. Bethune, an economist at the forecasting firm Global Insight, told the paper that figure compares with 4.5 percent in early 1981, the highest point since World War II. At its lowest point, in 1998, that share dropped to 1.9 percent, according to the June 9 report.