Year	Percent
1999-01-01	76.900
2000-01-01	76.750
2001-01-01	77.375
2002-01-01	76.725
2003-01-01	76.725
2004-01-01	76.550
2005-01-01	76.475
2006-01-01	76.400
2007-01-01	75.950
2008-01-01	76.350
2009-01-01	76.275
2010-01-01	76.050
2011-01-01	76.575
2012-01-01	77.150
2013-01-01	77.225
2014-01-01	77.600
2015-01-01	77.475
2016-01-01	78.250
2017-01-01	78.225