Year	Percent
1998-01-01	61.175
1999-01-01	62.975
2000-01-01	63.850
2001-01-01	64.350
2002-01-01	63.525
2003-01-01	63.275
2004-01-01	63.200
2005-01-01	63.650
2006-01-01	64.650
2007-01-01	65.450
2008-01-01	66.375
2009-01-01	62.925
2010-01-01	62.775
2011-01-01	63.500
2012-01-01	63.175
2013-01-01	62.200
2014-01-01	61.650
2015-01-01	61.325
2016-01-01	61.950
2017-01-01	62.575