Year	Percent
1998-01-01	90.275
1999-01-01	90.475
2000-01-01	90.575
2001-01-01	90.750
2002-01-01	91.025
2003-01-01	91.450
2004-01-01	91.525
2005-01-01	91.275
2006-01-01	91.350
2007-01-01	91.000
2008-01-01	91.025
2009-01-01	90.000
2010-01-01	89.425
2011-01-01	89.225
2012-01-01	89.375
2013-01-01	88.325
2014-01-01	87.700
2015-01-01	87.725
2016-01-01	88.225
2017-01-01	88.500