Year	Percent
1999-01-01	84.875
2000-01-01	84.225
2001-01-01	83.800
2002-01-01	83.575
2003-01-01	83.775
2004-01-01	84.050
2005-01-01	83.625
2006-01-01	84.075
2007-01-01	83.675
2008-01-01	84.300
2009-01-01	83.600
2010-01-01	82.625
2011-01-01	82.350
2012-01-01	81.450
2013-01-01	80.575
2014-01-01	81.100
2015-01-01	81.575
2016-01-01	82.650
2017-01-01	81.525