Year	Percent
2000-01-01	81.625
2001-01-01	81.150
2002-01-01	80.850
2003-01-01	79.700
2004-01-01	79.825
2005-01-01	79.925
2006-01-01	80.950
2007-01-01	82.275
2008-01-01	83.950
2009-01-01	83.500
2010-01-01	82.175
2011-01-01	82.150
2012-01-01	82.150
2013-01-01	81.550
2014-01-01	81.450
2015-01-01	80.725
2016-01-01	80.775
2017-01-01	80.450