Year	Percent
1999-01-01	63.950
2000-01-01	65.375
2001-01-01	64.700
2002-01-01	66.600
2003-01-01	68.025
2004-01-01	68.925
2005-01-01	70.025
2006-01-01	71.075
2007-01-01	71.725
2008-01-01	72.725
2009-01-01	73.075
2010-01-01	73.525
2011-01-01	73.900
2012-01-01	74.275
2013-01-01	74.300
2014-01-01	74.175
2015-01-01	74.300
2016-01-01	74.225
2017-01-01	73.900