(Portland, OR) -- Oregon gas prices are down nearly a dollar a gallon from this time last year. That's the largest decline in the nation, according to Triple-A. Over the last week, Oregon's average declined two cents to three-76 a gallon while the national average fell six cents to three-26. Low demand for gas and falling crude oil prices are the main reasons for the decline. Crude oil is now below 70 dollars a barrel. Tropical Storm Francine is expected to become a hurricane. If it affects oil production or gas refineries, it could affect prices.