Year	Ratio
1970-01-01	0.72233
1971-01-01	0.72308
1972-01-01	0.72339
1973-01-01	0.72452
1974-01-01	0.73211
1975-01-01	0.73803
1976-01-01	0.73780
1977-01-01	0.74109
1978-01-01	0.75382
1979-01-01	0.76622
1980-01-01	0.75805
1981-01-01	0.74926
1982-01-01	0.74624
1983-01-01	0.75912
1984-01-01	0.74979
1985-01-01	0.74245
1986-01-01	0.76777
1987-01-01	0.77938
1988-01-01	0.78534
1989-01-01	0.79328
1990-01-01	0.79654
1991-01-01	0.80251
1992-01-01	0.80997
1993-01-01	0.81542
1994-01-01	0.83135
1995-01-01	0.84153
1996-01-01	0.85008
1997-01-01	0.86122
1998-01-01	0.87583
1999-01-01	0.88910
2000-01-01	0.89457
2001-01-01	0.89748
2002-01-01	0.90377
2003-01-01	0.91980
2004-01-01	0.92132
2005-01-01	0.93069
2006-01-01	0.93657
2007-01-01	0.94396
2008-01-01	0.95220
2009-01-01	0.96407
2010-01-01	0.95876
2011-01-01	0.96270
2012-01-01	0.96683
2013-01-01	0.98036
2014-01-01	0.98558
2015-01-01	0.98427
2016-01-01	0.98543