Year	Percent
1998-01-01	73.600
1999-01-01	73.850
2000-01-01	74.125
2001-01-01	74.075
2002-01-01	74.350
2003-01-01	74.750
2004-01-01	74.975
2005-01-01	74.600
2006-01-01	74.550
2007-01-01	74.250
2008-01-01	74.300
2009-01-01	73.550
2010-01-01	73.100
2011-01-01	72.825
2012-01-01	73.725
2013-01-01	73.250
2014-01-01	73.575
2015-01-01	74.050
2016-01-01	74.800
2017-01-01	75.025