Year	Ratio
1970-01-01	0.53491
1971-01-01	0.53121
1972-01-01	0.52903
1973-01-01	0.53858
1974-01-01	0.54921
1975-01-01	0.54887
1976-01-01	0.55339
1977-01-01	0.55499
1978-01-01	0.55479
1979-01-01	0.55465
1980-01-01	0.56085
1981-01-01	0.57482
1982-01-01	0.59780
1983-01-01	0.60909
1984-01-01	0.61465
1985-01-01	0.62314
1986-01-01	0.63170
1987-01-01	0.64459
1988-01-01	0.65627
1989-01-01	0.66498
1990-01-01	0.67157
1991-01-01	0.67325
1992-01-01	0.67815
1993-01-01	0.67719
1994-01-01	0.66190
1995-01-01	0.69794
1996-01-01	0.69867
1997-01-01	0.69856
1998-01-01	0.69943
1999-01-01	0.69955
2000-01-01	0.70966
2001-01-01	0.69489
2002-01-01	0.71512
2003-01-01	0.73523
2004-01-01	0.72600
2005-01-01	0.74258
2006-01-01	0.74378
2007-01-01	0.75229
2008-01-01	0.75319
2009-01-01	0.75527
2010-01-01	0.76325
2011-01-01	0.77271
2012-01-01	0.77853
2013-01-01	0.78314
2014-01-01	0.78129
2015-01-01	0.79306
2016-01-01	0.79773