Year	Ratio
1971-01-01	0.319130003452301
1972-01-01	0.324710011482239
1973-01-01	0.347669988870621
1974-01-01	0.402379989624023
1976-01-01	0.545729994773865
1977-01-01	0.546609997749329
1978-01-01	0.572369992733002
1979-01-01	0.567489981651306
1980-01-01	0.576990008354187
1981-01-01	0.557049989700317
1982-01-01	0.543730020523071
1983-01-01	0.530870020389557
1984-01-01	0.541559994220734
1985-01-01	0.522329986095428
1986-01-01	0.500729978084564
2007-01-01	0.553229987621307