Year	Ratio
1970-01-01	0.27812
1971-01-01	0.27969
1972-01-01	0.28268
1973-01-01	0.28387
1974-01-01	0.29331
1975-01-01	0.30724
1976-01-01	0.31927
1977-01-01	0.34386
1978-01-01	0.34773
1979-01-01	0.36145
1980-01-01	0.36028
1981-01-01	0.37158
1982-01-01	0.40448
1983-01-01	0.39760
1984-01-01	0.39620
1985-01-01	0.42202
1986-01-01	0.43222
1987-01-01	0.43144
1988-01-01	0.45799
1989-01-01	0.46529
1990-01-01	0.47867
1991-01-01	0.48983
1992-01-01	0.49726
1993-01-01	0.50792
1994-01-01	0.51866
1995-01-01	0.53061
1996-01-01	0.57221
1997-01-01	0.58366
1998-01-01	0.60337
1999-01-01	0.62243
2000-01-01	0.63822
2001-01-01	0.66314
2002-01-01	0.67289
2003-01-01	0.66127
2004-01-01	0.65783
2005-01-01	0.69936
2006-01-01	0.71215
2007-01-01	0.69332
2008-01-01	0.69530
2009-01-01	0.70257
2010-01-01	0.72790
2011-01-01	0.78019
2012-01-01	0.86374
2013-01-01	0.91538
2014-01-01	0.95774
2015-01-01	0.95357
2016-01-01	0.96039