Year	Ratio
1970-01-01	0.70980
1971-01-01	0.71565
1972-01-01	0.72558
1973-01-01	0.73381
1974-01-01	0.74481
1975-01-01	0.74957
1976-01-01	0.75162
1977-01-01	0.76724
1978-01-01	0.77970
1979-01-01	0.78445
1980-01-01	0.79594
1981-01-01	0.80566
1982-01-01	0.80677
1983-01-01	0.80556
1984-01-01	0.81042
1985-01-01	0.81334
1986-01-01	0.81884
1987-01-01	0.82995
1988-01-01	0.81161
1989-01-01	0.83847
1990-01-01	0.82886
1991-01-01	0.83646
1992-01-01	0.84191
1993-01-01	0.84155
1994-01-01	0.84344
1995-01-01	0.83834
1996-01-01	0.84163
1997-01-01	0.84087
1998-01-01	0.83817
1999-01-01	0.84684
2000-01-01	0.85109
2001-01-01	0.85806
2002-01-01	0.85716
2003-01-01	0.86461
2004-01-01	0.87246
2005-01-01	0.88177
2006-01-01	0.89426
2007-01-01	0.90373
2008-01-01	0.91098
2009-01-01	0.91905
2010-01-01	0.92467
2011-01-01	0.92248
2012-01-01	0.93341
2013-01-01	0.93715
2014-01-01	0.93832
2015-01-01	0.94421
2016-01-01	0.94632