Year	Percent
1998-01-01	62.325
1999-01-01	62.975
2000-01-01	63.925
2001-01-01	64.750
2002-01-01	65.550
2003-01-01	66.400
2004-01-01	66.775
2005-01-01	67.775
2006-01-01	68.275
2007-01-01	68.750
2008-01-01	68.875
2009-01-01	68.850
2010-01-01	69.700
2011-01-01	69.500
2012-01-01	69.725
2013-01-01	69.775
2014-01-01	70.000
2015-01-01	70.350
2016-01-01	70.500
2017-01-01	71.650