Year	Percent
1998-01-01	64.500
1999-01-01	66.075
2000-01-01	66.750
2001-01-01	67.025
2002-01-01	66.950
2003-01-01	66.525
2004-01-01	66.275
2005-01-01	66.725
2006-01-01	67.200
2007-01-01	67.525
2008-01-01	67.900
2009-01-01	66.850
2010-01-01	66.375
2011-01-01	66.400
2012-01-01	66.325
2013-01-01	65.775
2014-01-01	65.725
2015-01-01	65.900
2016-01-01	65.650
2017-01-01	66.075