Year	Ratio
1970-01-01	0.70971
1971-01-01	0.71556
1972-01-01	0.72549
1973-01-01	0.73372
1974-01-01	0.74473
1975-01-01	0.74948
1976-01-01	0.75155
1977-01-01	0.76718
1978-01-01	0.77964
1979-01-01	0.78440
1980-01-01	0.79590
1981-01-01	0.80563
1982-01-01	0.80674
1983-01-01	0.80553
1984-01-01	0.81039
1985-01-01	0.81330
1986-01-01	0.81881
1987-01-01	0.82992
1988-01-01	0.81158
1989-01-01	0.83845
1990-01-01	0.82884
1991-01-01	0.83644
1992-01-01	0.84190
1993-01-01	0.84153
1994-01-01	0.84341
1995-01-01	0.83832
1996-01-01	0.84160
1997-01-01	0.84086
1998-01-01	0.83816
1999-01-01	0.84682
2000-01-01	0.85107
2001-01-01	0.85805
2002-01-01	0.85715
2003-01-01	0.86460
2004-01-01	0.87245
2005-01-01	0.88177
2006-01-01	0.89426
2007-01-01	0.90373
2008-01-01	0.91097
2009-01-01	0.91905
2010-01-01	0.92467
2011-01-01	0.92248
2012-01-01	0.93340
2013-01-01	0.93715
2014-01-01	0.93832
2015-01-01	0.94421
2016-01-01	0.94632