Year	Percent
1998-01-01	91.325
1999-01-01	89.525
2000-01-01	89.275
2001-01-01	89.700
2002-01-01	90.200
2003-01-01	89.700
2004-01-01	89.225
2005-01-01	89.875
2006-01-01	90.375
2007-01-01	91.725
2008-01-01	92.125
2009-01-01	90.500
2010-01-01	90.550
2011-01-01	90.900
2012-01-01	90.900
2013-01-01	91.150
2014-01-01	91.500
2015-01-01	91.875
2016-01-01	92.725
2017-01-01	93.725