Year	Ratio
1971-01-01	0.595070004463196
1972-01-01	0.667909979820251
1973-01-01	0.700559973716736
1977-01-01	0.729560017585754
1978-01-01	0.859109997749329
1979-01-01	0.812269985675812
1980-01-01	0.845300018787384
1981-01-01	0.851629972457886
1982-01-01	0.857980012893677
1984-01-01	0.750410020351410
1985-01-01	0.785880029201508
1986-01-01	0.839129984378815
1988-01-01	0.809780001640320
1990-01-01	0.794250011444092
1991-01-01	0.791429996490479
1992-01-01	0.798280000686646
1993-01-01	0.794650018215179
1994-01-01	0.792180001735687
1995-01-01	0.807430028915405
1996-01-01	0.810050010681152
1997-01-01	0.818830013275146
1998-01-01	0.828369975090027
1999-01-01	0.847720026969910
2000-01-01	0.850189983844757
2001-01-01	0.855949997901917
2002-01-01	0.858980000019073
2003-01-01	0.864019989967346
2004-01-01	0.872609972953796
2005-01-01	0.874559998512268
2006-01-01	0.879700005054474
2007-01-01	0.888800024986267
2008-01-01	0.899179995059967
2009-01-01	0.911800026893616
2010-01-01	0.922969996929169
2011-01-01	0.934350013732910
2012-01-01	0.942229986190796
2013-01-01	0.948069989681244
2014-01-01	0.953260004520416
2015-01-01	0.960569977760315
2016-01-01	0.961759984493256