(Portland, OR) -- Oregon had the sixth-largest weekly jump in gas prices across the country. The Oregon average increased 15 cents to $4.10 a gallon. The national average jumped a dime to $3.49. Prices are increasing, because of refinery maintenance and the switch to more expensive summer blends of fuel that produce less pollution. The price of crude oil is also up, because of drone attacks on Russian oil refineries. Russia is one of the world's major oil producers and the attacks are causing prices to rise as the supply might be threatened.