Year	Ratio
1970-01-01	0.60833
1971-01-01	0.60149
1972-01-01	0.61750
1973-01-01	0.62127
1974-01-01	0.63214
1975-01-01	0.63959
1976-01-01	0.64926
1977-01-01	0.66399
1978-01-01	0.68125
1979-01-01	0.68676
1980-01-01	0.70300
1981-01-01	0.71086
1982-01-01	0.73900
1983-01-01	0.74200
1984-01-01	0.74906
1985-01-01	0.73774
1986-01-01	0.74402
1987-01-01	0.76068
1988-01-01	0.74888
1989-01-01	0.75777
1990-01-01	0.76235
1991-01-01	0.77367
1992-01-01	0.77713
1993-01-01	0.78170
1994-01-01	0.78618
1995-01-01	0.77233
1996-01-01	0.76850
1997-01-01	0.77665
1998-01-01	0.78022
1999-01-01	0.80471
2000-01-01	0.81472
2001-01-01	0.82252
2002-01-01	0.82639
2003-01-01	0.83577
2004-01-01	0.83316
2005-01-01	0.86189
2006-01-01	0.88016
2007-01-01	0.88860
2008-01-01	0.89915
2009-01-01	0.91160
2010-01-01	0.91959
2011-01-01	0.92586
2012-01-01	0.92904
2013-01-01	0.93227
2014-01-01	0.93277
2015-01-01	0.94241
2016-01-01	0.94387