Year	Ratio
1970-01-01	0.53896
1971-01-01	0.53713
1972-01-01	0.54489
1973-01-01	0.55341
1974-01-01	0.56392
1975-01-01	0.56466
1976-01-01	0.58082
1977-01-01	0.59624
1978-01-01	0.60412
1979-01-01	0.61579
1980-01-01	0.62365
1981-01-01	0.63745
1982-01-01	0.65090
1983-01-01	0.66490
1984-01-01	0.67514
1985-01-01	0.68628
1986-01-01	0.69594
1987-01-01	0.70687
1988-01-01	0.71913
1989-01-01	0.72934
1990-01-01	0.75156
1991-01-01	0.76661
1992-01-01	0.78685
1993-01-01	0.79783
1994-01-01	0.80319
1995-01-01	0.82256
1996-01-01	0.82806
1997-01-01	0.83942
1998-01-01	0.85673
1999-01-01	0.87355
2000-01-01	0.88288
2001-01-01	0.88949
2002-01-01	0.90190
2003-01-01	0.91204
2004-01-01	0.91423
2005-01-01	0.92504
2006-01-01	0.93202
2007-01-01	0.93597
2008-01-01	0.93349
2009-01-01	0.92943
2010-01-01	0.92777
2011-01-01	0.93051
2012-01-01	0.92947
2013-01-01	0.92830
2014-01-01	0.92628
2015-01-01	0.92678
2016-01-01	0.92679