Gasoline prices that have been increasing for several years appear to be forcing South Dakota motorists to conserve.

The state Revenue Department, which collects taxes on each gallon of fuel, says 417 million gallons of regular gasoline and 10 percent ethanol were sold in South Dakota last year.

That was a reduction of about 1 percent from 2006, and it was nearly 4 percent less than 2005.

Gasoline hit an average all-time national high of $3.76 a gallon Wednesday.