(Portland, OR) -- Gas prices soared in Oregon over the last week. Triple-A reports the statewide average increased 18 cents a gallon to three-dollars-and-78-cents. It's the largest increase of any state. The national average declined a penny to three-27. Disruptions from the atmospheric river that hit California and the switch to more expensive summer blends of fuel caused West Coast prices to increase. Diesel in Oregon added four cents to four-18 a gallon.