Year	Ratio
1970-01-01	0.59385
1971-01-01	0.59692
1972-01-01	0.60028
1973-01-01	0.60625
1974-01-01	0.61302
1975-01-01	0.62066
1976-01-01	0.62574
1977-01-01	0.62446
1978-01-01	0.62924
1979-01-01	0.63187
1980-01-01	0.63254
1981-01-01	0.63386
1982-01-01	0.62992
1983-01-01	0.65389
1984-01-01	0.63069
1985-01-01	0.64609
1986-01-01	0.66491
1987-01-01	0.67516
1988-01-01	0.68403
1989-01-01	0.69305
1990-01-01	0.70008
1991-01-01	0.70730
1992-01-01	0.71606
1993-01-01	0.72335
1994-01-01	0.73886
1995-01-01	0.74632
1996-01-01	0.75522
1997-01-01	0.77423
1998-01-01	0.79484
1999-01-01	0.81480
2000-01-01	0.82073
2001-01-01	0.82723
2002-01-01	0.84062
2003-01-01	0.87348
2004-01-01	0.87001
2005-01-01	0.88018
2006-01-01	0.88932
2007-01-01	0.89987
2008-01-01	0.91487
2009-01-01	0.93547
2010-01-01	0.93918
2011-01-01	0.94563
2012-01-01	0.95249
2013-01-01	0.97304
2014-01-01	0.98268
2015-01-01	0.98464
2016-01-01	0.98924