Year	Ratio
1971-01-01	0.995620012283325
1972-01-01	0.987569987773895
1973-01-01	0.981639981269836
1974-01-01	0.978489995002747
1975-01-01	0.970319986343384
1976-01-01	0.964259982109070
1977-01-01	0.956879973411560
1978-01-01	0.944190025329590
1979-01-01	0.943889975547791
1980-01-01	0.939010024070740
1981-01-01	0.947329998016357
1982-01-01	0.949069976806641
1983-01-01	0.945879995822906
1984-01-01	0.949630022048950
1985-01-01	0.935750007629395
1986-01-01	0.938049972057343
1987-01-01	0.936569988727570
1988-01-01	0.936370015144348
1989-01-01	0.946539998054504
1990-01-01	0.960070013999939
1991-01-01	0.971220016479492
1992-01-01	0.985360026359558
1993-01-01	0.987590014934540
1994-01-01	0.990390002727509
1995-01-01	0.991500020027161
1996-01-01	0.966560006141663
1997-01-01	0.965929985046387
1998-01-01	0.961210012435913
1999-01-01	0.963959991931915
2000-01-01	0.960720002651215
2001-01-01	0.961210012435913
2002-01-01	0.965160012245178
2003-01-01	0.967610001564026
2004-01-01	0.966220021247864
2005-01-01	0.970570027828217
2006-01-01	0.973890006542206
2007-01-01	0.973829984664917
2008-01-01	0.978640019893646
2009-01-01	0.981649994850159
2010-01-01	0.982739984989166
2011-01-01	0.983160018920898
2012-01-01	0.983870029449463
2013-01-01	0.985520005226135
2014-01-01	0.950890004634857
2015-01-01	0.943379998207092