Year	Percent
1991-01-01	75.5899963378906
1992-01-01	75.6230010986328
1993-01-01	75.5950012207031
1994-01-01	75.6009979248047
1995-01-01	75.3560028076172
1996-01-01	75.0070037841797
1997-01-01	74.6399993896484
1998-01-01	74.1979980468750
1999-01-01	73.6859970092773
2000-01-01	74.7559967041016
2001-01-01	75.8389968872070
2002-01-01	76.9290008544922
2003-01-01	77.9840011596680
2004-01-01	78.9589996337891
2005-01-01	79.9869995117188
2006-01-01	79.8970031738281
2007-01-01	79.7880020141602
2008-01-01	79.6669998168945
2009-01-01	79.5370025634766
2010-01-01	79.3860015869141
2011-01-01	79.2480010986328
2012-01-01	79.1259994506836
2013-01-01	79.1129989624023
2014-01-01	78.8069992065430
2015-01-01	78.4990005493164
2016-01-01	78.1439971923828
2017-01-01	78.1699981689453