Year	Percent
1999-01-01	84.475
2000-01-01	85.750
2001-01-01	85.900
2002-01-01	85.575
2003-01-01	85.825
2004-01-01	85.925
2005-01-01	86.800
2006-01-01	87.475
2007-01-01	87.450
2008-01-01	84.250
2009-01-01	77.300
2010-01-01	75.850
2011-01-01	74.600
2012-01-01	71.275
2013-01-01	70.425
2014-01-01	72.475
2015-01-01	75.050
2016-01-01	77.375
2017-01-01	79.225