Year	Percent
1998-01-01	89.900
1999-01-01	90.575
2000-01-01	90.775
2001-01-01	90.875
2002-01-01	90.500
2003-01-01	90.050
2004-01-01	90.125
2005-01-01	90.250
2006-01-01	90.250
2007-01-01	90.400
2008-01-01	91.250
2009-01-01	90.650
2010-01-01	90.500
2011-01-01	90.875
2012-01-01	90.375
2013-01-01	90.075
2014-01-01	89.550
2015-01-01	89.550
2016-01-01	89.700
2017-01-01	89.775