Year	Ratio
1970-01-01	0.51343
1971-01-01	0.51221
1972-01-01	0.52693
1973-01-01	0.53932
1974-01-01	0.55236
1975-01-01	0.55789
1976-01-01	0.57425
1977-01-01	0.58929
1978-01-01	0.60018
1979-01-01	0.61399
1980-01-01	0.62460
1981-01-01	0.63972
1982-01-01	0.65402
1983-01-01	0.66891
1984-01-01	0.68062
1985-01-01	0.69328
1986-01-01	0.70092
1987-01-01	0.70838
1988-01-01	0.71702
1989-01-01	0.72776
1990-01-01	0.74828
1991-01-01	0.76748
1992-01-01	0.78455
1993-01-01	0.79906
1994-01-01	0.80884
1995-01-01	0.83290
1996-01-01	0.84679
1997-01-01	0.86494
1998-01-01	0.88054
1999-01-01	0.89597
2000-01-01	0.90592
2001-01-01	0.91149
2002-01-01	0.91612
2003-01-01	0.92308
2004-01-01	0.92985
2005-01-01	0.93866
2006-01-01	0.94498
2007-01-01	0.95839
2008-01-01	0.95034
2009-01-01	0.94728
2010-01-01	0.94601
2011-01-01	0.94626
2012-01-01	0.94505
2013-01-01	0.94213
2014-01-01	0.93991
2015-01-01	0.93989
2016-01-01	0.94021