Year	Ratio
1970-01-01	0.48103
1971-01-01	0.48046
1972-01-01	0.49921
1973-01-01	0.51348
1974-01-01	0.52736
1975-01-01	0.53447
1976-01-01	0.55296
1977-01-01	0.57009
1978-01-01	0.58328
1979-01-01	0.59855
1980-01-01	0.60945
1981-01-01	0.62583
1982-01-01	0.64043
1983-01-01	0.65605
1984-01-01	0.66812
1985-01-01	0.68129
1986-01-01	0.68924
1987-01-01	0.69481
1988-01-01	0.70262
1989-01-01	0.71322
1990-01-01	0.73620
1991-01-01	0.75724
1992-01-01	0.77621
1993-01-01	0.79159
1994-01-01	0.80200
1995-01-01	0.82747
1996-01-01	0.84153
1997-01-01	0.86015
1998-01-01	0.87683
1999-01-01	0.89389
2000-01-01	0.90420
2001-01-01	0.90915
2002-01-01	0.91311
2003-01-01	0.92011
2004-01-01	0.92630
2005-01-01	0.93471
2006-01-01	0.94287
2007-01-01	0.95812
2008-01-01	0.94982
2009-01-01	0.94874
2010-01-01	0.95031
2011-01-01	0.95337
2012-01-01	0.95092
2013-01-01	0.94915
2014-01-01	0.95401
2015-01-01	0.95427
2016-01-01	0.95447