Year	Ratio
1971-01-01	0.744319975376129
1972-01-01	0.891340017318726
1973-01-01	0.879329979419708
1974-01-01	0.857400000095367
1975-01-01	0.873539984226227
1976-01-01	0.751259982585907
1977-01-01	0.736660003662109
1978-01-01	0.744960010051727
1979-01-01	0.767960011959076
1980-01-01	0.888679981231689
1981-01-01	0.541970014572144
1982-01-01	0.533909976482391
1983-01-01	0.468769997358322
1984-01-01	0.554099977016449
1985-01-01	0.519420027732849
1986-01-01	0.522700011730194
1987-01-01	0.442739993333817
2001-01-01	1.166139960289000
2003-01-01	1.192569971084590
2006-01-01	1.134490013122560
2008-01-01	0.963609993457794
2010-01-01	1.108929991722110
2012-01-01	1.135310053825380
2015-01-01	1.109789967536930