Year	Ratio
1971-01-01	0.432370007038116
1972-01-01	0.477479994297028
1973-01-01	0.497880011796951
1974-01-01	0.546259999275208
1975-01-01	0.588509976863861
1976-01-01	0.555440008640289
1982-01-01	0.726949989795685
1983-01-01	0.735400021076202
1984-01-01	0.743290007114410
1985-01-01	0.734549999237061
1986-01-01	0.715219974517822
1987-01-01	0.712249994277954
1988-01-01	0.721560001373291
1989-01-01	0.732779979705811
1990-01-01	0.735310018062592
1991-01-01	0.721859991550446
1992-01-01	0.730620026588440
1993-01-01	0.782890021800995
1994-01-01	0.776740014553070
1995-01-01	0.778949975967407
1996-01-01	0.753530025482178
1997-01-01	0.749319970607758
1998-01-01	0.755739986896515
1999-01-01	0.716700017452240
2000-01-01	0.739120006561279
2001-01-01	0.753099977970123
2002-01-01	0.770290017127991
2004-01-01	0.797379970550537
2005-01-01	0.824500024318695
2006-01-01	0.818819999694824
2007-01-01	0.865289986133575
2008-01-01	0.891179978847504
2009-01-01	0.899209976196289
2011-01-01	0.908789992332459
2012-01-01	0.900550007820129
2013-01-01	0.882780015468597
2014-01-01	0.871980011463165
2015-01-01	0.888149976730347
2016-01-01	0.887419998645782
2017-01-01	0.891099989414215