Year	Ratio
1970-01-01	0.68552
1971-01-01	0.68368
1972-01-01	0.68106
1973-01-01	0.68598
1974-01-01	0.68563
1975-01-01	0.67583
1976-01-01	0.66846
1977-01-01	0.66186
1978-01-01	0.66116
1979-01-01	0.65124
1980-01-01	0.64227
1981-01-01	0.64641
1982-01-01	0.65275
1983-01-01	0.61478
1984-01-01	0.59294
1985-01-01	0.64918
1986-01-01	0.71156
1987-01-01	0.73309
1988-01-01	0.73785
1989-01-01	0.74576
1990-01-01	0.75843
1991-01-01	0.76821
1992-01-01	0.77814
1993-01-01	0.78373
1994-01-01	0.78550
1995-01-01	0.80415
1996-01-01	0.81132
1997-01-01	0.81547
1998-01-01	0.81562
1999-01-01	0.81726
2000-01-01	0.80250
2001-01-01	0.79705
2002-01-01	0.77733
2003-01-01	0.78382
2004-01-01	0.78089
2005-01-01	0.78739
2006-01-01	0.78586
2007-01-01	0.77737
2008-01-01	0.79629
2009-01-01	0.80890
2010-01-01	0.82044
2011-01-01	0.82677
2012-01-01	0.84697
2013-01-01	0.86149
2014-01-01	0.86636
2015-01-01	0.86526
2016-01-01	0.86682