Year	Percent
2001-01-01	82.450
2002-01-01	82.375
2003-01-01	81.700
2004-01-01	80.875
2005-01-01	80.800
2006-01-01	81.525
2007-01-01	82.975
2008-01-01	83.475
2009-01-01	81.950
2010-01-01	80.875
2011-01-01	82.200
2012-01-01	82.525
2013-01-01	82.750
2014-01-01	82.800
2015-01-01	83.275
2016-01-01	83.750
2017-01-01	84.125