Year	Percent
1998-01-01	88.800
1999-01-01	88.225
2000-01-01	88.525
2001-01-01	88.500
2002-01-01	88.675
2003-01-01	89.225
2004-01-01	89.250
2005-01-01	89.475
2006-01-01	89.975
2007-01-01	90.075
2008-01-01	90.125
2009-01-01	88.300
2010-01-01	85.275
2011-01-01	79.900
2012-01-01	73.925
2013-01-01	71.375
2014-01-01	71.750
2015-01-01	73.650
2016-01-01	76.000
2017-01-01	77.500