Year	Ratio
1981-01-01	0.986379981040955
1986-01-01	0.984600007534027
1989-01-01	0.989769995212555
1990-01-01	0.990140020847321
1991-01-01	1.000849962234500
1992-01-01	0.996070027351379
1993-01-01	0.991519987583160
1994-01-01	0.997290015220642
1995-01-01	0.992630004882813
1999-01-01	1.002640008926390
2000-01-01	0.991720020771027
2001-01-01	0.999989986419678
2002-01-01	0.994989991188049
2003-01-01	0.994960010051727
2004-01-01	0.993889987468719
2005-01-01	0.986240029335022
2006-01-01	0.989260017871857
2007-01-01	0.983650028705597
2008-01-01	0.978919982910156
2009-01-01	0.982850015163422
2010-01-01	0.995959997177124
2011-01-01	0.991829991340637
2012-01-01	0.997659981250763
2013-01-01	1.000679969787600
2014-01-01	0.995729982852936
2015-01-01	0.989929974079132