Year	Ratio
1971-01-01	0.611119985580444
1972-01-01	0.620490014553070
1973-01-01	0.594699978828430
1974-01-01	0.609730005264282
1975-01-01	0.600589990615845
1976-01-01	0.609269976615906
1977-01-01	0.619000017642975
1978-01-01	0.623170018196106
1980-01-01	0.641979992389679
1981-01-01	0.681550025939941
1982-01-01	0.657540023326874
1983-01-01	0.664200007915497
1984-01-01	0.668089985847473
1985-01-01	0.670189976692200
1988-01-01	0.675300002098084
1989-01-01	0.705250024795532
1990-01-01	0.677339971065521
1991-01-01	0.686839997768402
2000-01-01	0.920849978923798
2001-01-01	0.698379993438721
2011-01-01	0.940840005874634
2012-01-01	0.983359992504120
2013-01-01	0.995899975299835
2015-01-01	1.009889960289000
2016-01-01	1.006749987602230