Year	Percent
1998-01-01	89.800
1999-01-01	89.600
2000-01-01	89.975
2001-01-01	90.150
2002-01-01	89.300
2003-01-01	87.850
2004-01-01	87.600
2005-01-01	86.825
2006-01-01	87.500
2007-01-01	87.250
2008-01-01	87.625
2009-01-01	84.675
2010-01-01	84.075
2011-01-01	81.750
2012-01-01	78.625
2013-01-01	77.075
2014-01-01	80.625
2015-01-01	81.825
2016-01-01	83.000
2017-01-01	85.600