Year	Percent
1998-01-01	73.500
1999-01-01	73.275
2000-01-01	72.650
2001-01-01	72.250
2002-01-01	72.375
2003-01-01	71.800
2004-01-01	71.750
2005-01-01	72.225
2006-01-01	72.175
2007-01-01	72.175
2008-01-01	71.975
2009-01-01	72.175
2010-01-01	71.975
2011-01-01	71.575
2012-01-01	71.850
2013-01-01	72.400
2014-01-01	72.550
2015-01-01	72.450
2016-01-01	73.100
2017-01-01	73.375