Average Gasoline Prices (per gallon) If it cost $6 to fill a gas tank in 1970, how much would it have cost to fill the same tank in 1960? Price as a Percentage Price Index of 1970 Price1970-100) Year Price 960 $0. 1970 S0.36 1980 $1.22 1990 $1.23 2000 $1.56 2010 $2.84 311 861% 100.0% 338 9% 341.7% 433 3% 788 9% 86.1 100.0 338.9 341.7 433.3 88.9 it would have cost S 5 14 in 1960 Round to the nearest cent as needed)