Year	Ratio
1971-01-01	0.77255
1972-01-01	0.76554
1973-01-01	0.75997
1974-01-01	0.76490
1975-01-01	0.76655
1976-01-01	0.76069
1977-01-01	0.77233
1978-01-01	0.79759
1979-01-01	0.79582
1980-01-01	0.78748
1981-01-01	0.76763
1982-01-01	0.76610
1983-01-01	0.77963
1984-01-01	0.78716
1985-01-01	0.79745
1986-01-01	0.79641
1987-01-01	0.81739
1988-01-01	0.82035
1989-01-01	0.83019
1990-01-01	0.83221
1991-01-01	0.83719
1992-01-01	0.85082
1993-01-01	0.85737
1994-01-01	0.88612
1995-01-01	0.89954
1996-01-01	0.91082
1997-01-01	0.91589
1998-01-01	0.92979
1999-01-01	0.94408
2000-01-01	0.95056
2001-01-01	0.95415
2002-01-01	0.95761
2003-01-01	0.96099
2004-01-01	0.97261
2005-01-01	0.98444
2006-01-01	0.99512
2007-01-01	1.00140
2008-01-01	1.00741
2009-01-01	1.01522
2010-01-01	0.99884
2011-01-01	1.00172
2012-01-01	1.00822
2013-01-01	1.00600
2014-01-01	1.01197
2015-01-01	1.01198
2016-01-01	1.01357