Year	Percent
1998-01-01	52.300
1999-01-01	53.325
2000-01-01	55.600
2001-01-01	58.475
2002-01-01	61.275
2003-01-01	63.225
2004-01-01	64.825
2005-01-01	66.000
2006-01-01	66.450
2007-01-01	68.050
2008-01-01	68.850
2009-01-01	68.150
2010-01-01	69.075
2011-01-01	70.050
2012-01-01	68.725
2013-01-01	68.450
2014-01-01	67.775
2015-01-01	67.500
2016-01-01	68.025
2017-01-01	68.350