Year	Percent
1998-01-01	66.075
1999-01-01	66.025
2000-01-01	65.700
2001-01-01	67.375
2002-01-01	69.000
2003-01-01	70.150
2004-01-01	68.250
2005-01-01	71.250
2006-01-01	73.150
2007-01-01	74.550
2008-01-01	74.475
2009-01-01	76.325
2010-01-01	76.850
2011-01-01	77.225
2012-01-01	76.000
2013-01-01	76.600
2014-01-01	76.900
2015-01-01	78.325
2016-01-01	77.250
2017-01-01	77.900