Year	Percent
1998-01-01	88.525
1999-01-01	88.575
2000-01-01	88.400
2001-01-01	88.425
2002-01-01	88.200
2003-01-01	87.775
2004-01-01	87.800
2005-01-01	88.300
2006-01-01	88.150
2007-01-01	87.775
2008-01-01	87.300
2009-01-01	87.650
2010-01-01	87.825
2011-01-01	88.050
2012-01-01	88.325
2013-01-01	89.075
2014-01-01	88.750
2015-01-01	88.600
2016-01-01	88.900
2017-01-01	89.050