Year	Percent
1999-01-01	81.525
2000-01-01	82.875
2001-01-01	83.925
2002-01-01	83.875
2003-01-01	84.825
2004-01-01	84.100
2005-01-01	82.125
2006-01-01	81.200
2007-01-01	80.675
2008-01-01	82.125
2009-01-01	80.750
2010-01-01	80.875
2011-01-01	80.400
2012-01-01	80.375
2013-01-01	80.525
2014-01-01	80.375
2015-01-01	80.775
2016-01-01	81.450
2017-01-01	79.800