Year	Percent
1998-01-01	71.750
1999-01-01	71.100
2000-01-01	71.525
2001-01-01	71.275
2002-01-01	71.875
2003-01-01	72.800
2004-01-01	73.000
2005-01-01	73.425
2006-01-01	73.925
2007-01-01	74.200
2008-01-01	74.375
2009-01-01	72.950
2010-01-01	70.350
2011-01-01	65.350
2012-01-01	60.075
2013-01-01	57.900
2014-01-01	57.975
2015-01-01	59.275
2016-01-01	60.975
2017-01-01	62.725