Year	Ratio
1970-01-01	0.56414
1971-01-01	0.55874
1972-01-01	0.55453
1973-01-01	0.55332
1974-01-01	0.55549
1975-01-01	0.55733
1976-01-01	0.56553
1977-01-01	0.54259
1978-01-01	0.53987
1979-01-01	0.55925
1980-01-01	0.56702
1981-01-01	0.57330
1982-01-01	0.57762
1983-01-01	0.58489
1984-01-01	0.58831
1985-01-01	0.60400
1986-01-01	0.59012
1987-01-01	0.59404
1988-01-01	0.64594
1989-01-01	0.67224
1990-01-01	0.70440
1991-01-01	0.73399
1992-01-01	0.73570
1993-01-01	0.75239
1994-01-01	0.75155
1995-01-01	0.76165
1996-01-01	0.77124
1997-01-01	0.78229
1998-01-01	0.80625
1999-01-01	0.82665
2000-01-01	0.85227
2001-01-01	0.87044
2002-01-01	0.90014
2003-01-01	0.94692
2004-01-01	0.93616
2005-01-01	0.96382
2006-01-01	0.99745
2007-01-01	0.96270
2008-01-01	1.03934
2009-01-01	1.03611
2010-01-01	1.03593
2011-01-01	1.03999
2012-01-01	1.03525
2013-01-01	1.03253
2014-01-01	1.03791
2015-01-01	1.06382
2016-01-01	1.09161