Year	Percent
1999-01-01	59.925
2000-01-01	61.675
2001-01-01	65.375
2002-01-01	67.375
2003-01-01	69.050
2004-01-01	72.050
2005-01-01	72.925
2006-01-01	73.300
2007-01-01	74.275
2008-01-01	74.875
2009-01-01	75.325
2010-01-01	75.175
2011-01-01	75.700
2012-01-01	74.325
2013-01-01	72.575
2014-01-01	70.475
2015-01-01	68.950
2016-01-01	67.700
2017-01-01	67.550