Year	Ratio
1973-01-01	0.75543
1974-01-01	0.72989
1975-01-01	0.71672
1976-01-01	0.70326
1977-01-01	0.71187
1978-01-01	0.69304
1979-01-01	0.66329
1980-01-01	0.64999
1981-01-01	0.61337
1982-01-01	0.64110
1983-01-01	0.65636
1984-01-01	0.66251
1985-01-01	0.64540
1986-01-01	0.62041
1987-01-01	0.62001
1988-01-01	0.63442
1989-01-01	0.65682
1990-01-01	0.67030
1991-01-01	0.70578
1992-01-01	0.72898
1993-01-01	0.75136
1994-01-01	0.73847
1995-01-01	0.73883
1996-01-01	0.73822
1997-01-01	0.76956
1998-01-01	0.80935
1999-01-01	0.85655
2000-01-01	0.87039
2001-01-01	0.84636
2002-01-01	0.88465
2003-01-01	0.88733
2004-01-01	0.91712
2005-01-01	0.92424
2006-01-01	0.96516
2007-01-01	1.00696
2008-01-01	1.02317
2009-01-01	1.04301
2010-01-01	1.05710
2011-01-01	1.07293
2012-01-01	1.10658
2013-01-01	1.13335
2014-01-01	1.15742
2015-01-01	1.17386
2016-01-01	1.19194