Year	Percent
1998-01-01	81.725
1999-01-01	83.400
2000-01-01	84.225
2001-01-01	84.675
2002-01-01	83.825
2003-01-01	83.300
2004-01-01	83.800
2005-01-01	84.450
2006-01-01	85.150
2007-01-01	85.975
2008-01-01	87.300
2009-01-01	84.250
2010-01-01	83.850
2011-01-01	84.850
2012-01-01	84.450
2013-01-01	83.900
2014-01-01	82.725
2015-01-01	82.525
2016-01-01	83.025
2017-01-01	83.250