Year	Ratio
1971-01-01	0.848349988460541
1972-01-01	0.868110001087189
1973-01-01	0.884410023689270
1974-01-01	0.894609987735748
1975-01-01	0.901780009269714
1976-01-01	0.918770015239716
1977-01-01	0.921720027923584
1978-01-01	0.931540012359619
1979-01-01	0.941550016403198
1980-01-01	0.946300029754639
1981-01-01	0.953700006008148
1982-01-01	0.960080027580261
1983-01-01	0.963959991931915
1984-01-01	0.963299989700317
1985-01-01	0.973249971866608
1986-01-01	0.957059979438782
1987-01-01	0.953639984130859
1988-01-01	0.935819983482361
1989-01-01	0.935970008373261
1990-01-01	0.926100015640259
1991-01-01	0.925689995288849
1992-01-01	0.933770000934601
1993-01-01	0.954230010509491
1994-01-01	0.933979988098145
1995-01-01	0.947939991950989
1996-01-01	0.944069981575012
1997-01-01	0.957579970359802
1998-01-01	0.961920022964478
1999-01-01	0.953890025615692
2000-01-01	0.957750022411346
2001-01-01	0.967830002307892
2002-01-01	0.972270011901855
2003-01-01	0.985360026359558
2004-01-01	0.984000027179718
2005-01-01	0.980180025100708
2006-01-01	0.981400012969971
2007-01-01	0.979560017585754
2008-01-01	0.981029987335205
2009-01-01	0.983030021190643
2010-01-01	0.986299991607666
2011-01-01	0.987990021705627
2012-01-01	0.982919991016388
2015-01-01	1.015339970588680
2016-01-01	1.016589999198910