Year	Percent
1998-01-01	75.950
1999-01-01	74.225
2000-01-01	73.725
2001-01-01	74.400
2002-01-01	74.725
2003-01-01	73.475
2004-01-01	73.350
2005-01-01	73.975
2006-01-01	74.525
2007-01-01	74.925
2008-01-01	75.225
2009-01-01	74.050
2010-01-01	73.375
2011-01-01	74.325
2012-01-01	74.575
2013-01-01	75.500
2014-01-01	75.750
2015-01-01	76.750
2016-01-01	78.400
2017-01-01	79.325