Year	Percent
1998-01-01	60.050
1999-01-01	61.500
2000-01-01	62.025
2001-01-01	61.750
2002-01-01	63.575
2003-01-01	65.400
2004-01-01	67.700
2005-01-01	68.400
2006-01-01	69.225
2007-01-01	69.175
2008-01-01	69.550
2009-01-01	71.150
2010-01-01	72.350
2011-01-01	72.800
2012-01-01	73.975
2013-01-01	74.300
2014-01-01	75.600
2015-01-01	77.675
2016-01-01	77.750
2017-01-01	77.000