Year	Ratio
1970-01-01	0.96963
1971-01-01	0.96791
1972-01-01	0.95998
1973-01-01	0.96571
1974-01-01	0.97018
1975-01-01	0.96442
1976-01-01	0.96362
1977-01-01	0.97074
1978-01-01	0.96881
1979-01-01	0.97217
1980-01-01	0.97740
1981-01-01	0.97623
1982-01-01	0.97617
1983-01-01	0.97389
1984-01-01	0.97454
1985-01-01	0.97944
1986-01-01	0.98130
1987-01-01	0.98163
1988-01-01	0.98706
1989-01-01	0.98606
1990-01-01	0.98897
1991-01-01	0.98113
1992-01-01	0.98202
1993-01-01	0.97831
1994-01-01	0.97399
1995-01-01	0.97316
1996-01-01	0.97152
1997-01-01	0.97072
1998-01-01	0.96908
1999-01-01	0.97694
2000-01-01	0.97216
2001-01-01	0.97133
2002-01-01	0.97011
2003-01-01	0.97349
2004-01-01	0.97423
2005-01-01	0.97045
2006-01-01	0.97281
2007-01-01	0.97437
2008-01-01	0.96976
2009-01-01	0.97599
2010-01-01	0.96996
2011-01-01	0.97077
2012-01-01	0.98355
2013-01-01	0.97903
2014-01-01	0.98197
2015-01-01	0.98494
2016-01-01	0.98246