Year	Percent
1999-01-01	69.275
2000-01-01	71.200
2001-01-01	72.475
2002-01-01	72.625
2003-01-01	73.200
2004-01-01	73.600
2005-01-01	75.100
2006-01-01	76.050
2007-01-01	76.125
2008-01-01	73.325
2009-01-01	66.475
2010-01-01	64.775
2011-01-01	63.350
2012-01-01	60.300
2013-01-01	59.225
2014-01-01	60.675
2015-01-01	62.900
2016-01-01	64.750
2017-01-01	66.500