Year	Ratio
1970-01-01	0.41831
1971-01-01	0.41866
1972-01-01	0.42562
1973-01-01	0.43366
1974-01-01	0.44240
1975-01-01	0.45162
1976-01-01	0.45406
1977-01-01	0.45530
1978-01-01	0.46037
1979-01-01	0.46676
1980-01-01	0.47478
1981-01-01	0.48218
1982-01-01	0.48490
1983-01-01	0.53406
1984-01-01	0.50831
1985-01-01	0.51724
1986-01-01	0.53418
1987-01-01	0.54075
1988-01-01	0.55325
1989-01-01	0.56601
1990-01-01	0.57732
1991-01-01	0.59381
1992-01-01	0.60898
1993-01-01	0.62498
1994-01-01	0.64281
1995-01-01	0.64935
1996-01-01	0.66036
1997-01-01	0.68371
1998-01-01	0.70585
1999-01-01	0.72783
2000-01-01	0.73797
2001-01-01	0.74920
2002-01-01	0.77503
2003-01-01	0.82678
2004-01-01	0.81931
2005-01-01	0.83738
2006-01-01	0.84621
2007-01-01	0.86487
2008-01-01	0.88689
2009-01-01	0.91600
2010-01-01	0.92357
2011-01-01	0.93720
2012-01-01	0.94221
2013-01-01	0.98312
2014-01-01	0.99407
2015-01-01	0.99496
2016-01-01	0.99832