Year	Ratio
1970-01-01	0.970049977302551
1971-01-01	0.946550011634827
1972-01-01	0.948629975318909
1973-01-01	0.946269989013672
1974-01-01	0.945670008659363
1975-01-01	0.945020020008087
1976-01-01	0.943669974803925
1977-01-01	0.955649971961975
1978-01-01	0.955060005187988
1979-01-01	0.960110008716583
1980-01-01	0.951290011405945
1981-01-01	0.969529986381531
1982-01-01	0.982079982757568
1983-01-01	0.975440025329590
1984-01-01	0.967800021171570
1986-01-01	0.977760016918182
1987-01-01	0.955359995365143
1988-01-01	0.971870005130768
1989-01-01	0.959029972553253
1991-01-01	0.944459974765778
1992-01-01	0.955190002918243
1993-01-01	0.968429982662201
1994-01-01	0.963249981403351
1995-01-01	0.949599981307983
1996-01-01	0.953570008277893
1997-01-01	0.943000018596649
1998-01-01	0.936770021915436
1999-01-01	0.929790019989014
2000-01-01	0.947830021381378
2001-01-01	0.954460024833679
2002-01-01	0.964500010013580
2003-01-01	0.975189983844757
2004-01-01	0.966319978237152
2005-01-01	0.961430013179779
2006-01-01	0.953700006008148
2007-01-01	0.958299994468689
2008-01-01	0.974219977855682
2009-01-01	0.987860023975372
2010-01-01	0.995549976825714
2011-01-01	0.993099987506866
2012-01-01	0.989199995994568
2013-01-01	0.993380010128021
2014-01-01	0.996309995651245
2015-01-01	0.991779983043671
2016-01-01	0.991209983825684