Year	Ratio
1970-01-01	0.56491
1971-01-01	0.56108
1972-01-01	0.55739
1973-01-01	0.56027
1974-01-01	0.56360
1975-01-01	0.55505
1976-01-01	0.55031
1977-01-01	0.54758
1978-01-01	0.54574
1979-01-01	0.54352
1980-01-01	0.55512
1981-01-01	0.56290
1982-01-01	0.58773
1983-01-01	0.59347
1984-01-01	0.60312
1985-01-01	0.61514
1986-01-01	0.62748
1987-01-01	0.63946
1988-01-01	0.64536
1989-01-01	0.65338
1990-01-01	0.66022
1991-01-01	0.66781
1992-01-01	0.67121
1993-01-01	0.66761
1994-01-01	0.65009
1995-01-01	0.68130
1996-01-01	0.68117
1997-01-01	0.67991
1998-01-01	0.67902
1999-01-01	0.68414
2000-01-01	0.68656
2001-01-01	0.68935
2002-01-01	0.69320
2003-01-01	0.70510
2004-01-01	0.69485
2005-01-01	0.70582
2006-01-01	0.70762
2007-01-01	0.71857
2008-01-01	0.72925
2009-01-01	0.74176
2010-01-01	0.75869
2011-01-01	0.78074
2012-01-01	0.79383
2013-01-01	0.81005
2014-01-01	0.81668
2015-01-01	0.82722
2016-01-01	0.82941