Year	Ratio
1971-01-01	0.408859997987747
1972-01-01	0.421139985322952
1978-01-01	0.469119995832443
1979-01-01	0.481189996004105
1980-01-01	0.486649990081787
1981-01-01	0.493250012397766
1982-01-01	0.513769984245300
1983-01-01	0.499339997768402
1984-01-01	0.492549985647202
1985-01-01	0.499150007963181
1986-01-01	0.496980011463165
1988-01-01	0.506720006465912
1989-01-01	0.498380005359650
1990-01-01	0.509429991245270
1992-01-01	0.534160017967224
1996-01-01	0.606729984283447
1997-01-01	0.601920008659363
1998-01-01	0.618770003318787
1999-01-01	0.643050014972687
2000-01-01	0.651109993457794
2001-01-01	0.659770011901855
2002-01-01	0.670490026473999
2004-01-01	0.721520006656647
2005-01-01	0.747389972209930
2006-01-01	0.759249985218048
2008-01-01	0.790650010108948
2010-01-01	0.871699988842011
2011-01-01	0.916960000991821
2012-01-01	0.941959977149963
2013-01-01	0.970139980316162
2014-01-01	0.998319983482361
2015-01-01	0.979009985923767
2016-01-01	1.011260032653810