Year	Percent
1998-01-01	77.575
1999-01-01	77.450
2000-01-01	77.450
2001-01-01	76.950
2002-01-01	77.200
2003-01-01	77.700
2004-01-01	78.300
2005-01-01	78.375
2006-01-01	78.525
2007-01-01	78.350
2008-01-01	78.450
2009-01-01	78.525
2010-01-01	78.350
2011-01-01	77.225
2012-01-01	76.875
2013-01-01	76.875
2014-01-01	76.050
2015-01-01	75.850
2016-01-01	76.150
2017-01-01	76.425