Gas prices took a substantial tumble in the last week to some of the lowest summer gas prices in a decade. Nashville prices at the pump dropped from $2.18 last week to $2.04 today. Statewide prices dropped almost a dime per gallon in the last seven weeks, from an average of $2.27 to $2.18. Statewide averages last year were $2.78, and $2.52 last month. The national average price is $2.15, down from $2.31 last month and $2.74 a year ago. The Midwest has some of the highest refinery utilization rates in the county at 95.9 percent, which means gasoline output and supply levels are high, holding down prices. Eleven states have average per gallon prices below $2.00, including neighboring Missouri at $1.91 and Kentucky at $1.99.