Year	Percent
1998-01-01	65.975
1999-01-01	66.025
2000-01-01	66.225
2001-01-01	66.175
2002-01-01	66.425
2003-01-01	66.750
2004-01-01	66.600
2005-01-01	66.200
2006-01-01	66.150
2007-01-01	65.875
2008-01-01	65.925
2009-01-01	65.175
2010-01-01	64.800
2011-01-01	64.575
2012-01-01	65.275
2013-01-01	64.775
2014-01-01	64.975
2015-01-01	65.375
2016-01-01	65.950
2017-01-01	66.275