Year	Percent
1999-01-01	83.950
2000-01-01	84.125
2001-01-01	84.400
2002-01-01	84.050
2003-01-01	83.475
2004-01-01	83.725
2005-01-01	84.525
2006-01-01	86.075
2007-01-01	86.125
2008-01-01	87.500
2009-01-01	84.675
2010-01-01	82.825
2011-01-01	82.300
2012-01-01	81.875
2013-01-01	82.000
2014-01-01	81.950
2015-01-01	82.175
2016-01-01	82.525
2017-01-01	81.675