Year	Percent
1998-01-01	84.025
1999-01-01	84.775
2000-01-01	84.900
2001-01-01	84.950
2002-01-01	85.450
2003-01-01	84.775
2004-01-01	84.550
2005-01-01	85.050
2006-01-01	85.250
2007-01-01	85.575
2008-01-01	85.900
2009-01-01	85.725
2010-01-01	84.425
2011-01-01	84.325
2012-01-01	84.100
2013-01-01	83.325
2014-01-01	83.600
2015-01-01	83.600
2016-01-01	82.750
2017-01-01	83.625