Year	Ratio
1970-01-01	0.697880029678345
1971-01-01	0.767139971256256
1973-01-01	0.799679994583130
1974-01-01	0.815500020980835
1975-01-01	0.829119980335236
1976-01-01	0.839380025863647
1977-01-01	0.853659987449646
1978-01-01	0.868380010128021
1979-01-01	0.870329976081848
1980-01-01	0.901329994201660
1981-01-01	0.873130023479462
1983-01-01	0.897639989852905
1984-01-01	0.921880006790161
1986-01-01	0.917490005493164
1987-01-01	0.914020001888275
1989-01-01	0.922699987888336
1990-01-01	0.927590012550354
1991-01-01	0.931219995021820
1992-01-01	0.935190021991730
1993-01-01	0.949909985065460
1994-01-01	0.954020023345947
1995-01-01	0.955770015716553
1996-01-01	0.958469986915588
1997-01-01	0.960489988327026
1998-01-01	0.967890024185181
1999-01-01	0.973510026931763
2000-01-01	0.973710000514984
2001-01-01	0.976050019264221
2002-01-01	0.978190004825592
2003-01-01	0.985210001468658
2004-01-01	0.988569974899292
2005-01-01	0.990220010280609
2006-01-01	0.990800023078918
2007-01-01	0.990199983119965
2008-01-01	0.986410021781921
2009-01-01	0.981440007686615
2010-01-01	0.979979991912842
2011-01-01	0.978590011596680
2012-01-01	0.979179978370667
2013-01-01	0.971759974956512
2014-01-01	0.969860017299652
2015-01-01	0.972150027751923
2016-01-01	0.976899981498718