Year	Percent
1998-01-01	72.350
1999-01-01	73.850
2000-01-01	74.525
2001-01-01	75.025
2002-01-01	74.950
2003-01-01	74.450
2004-01-01	74.225
2005-01-01	74.725
2006-01-01	75.200
2007-01-01	75.550
2008-01-01	75.975
2009-01-01	74.975
2010-01-01	74.500
2011-01-01	74.975
2012-01-01	75.225
2013-01-01	75.150
2014-01-01	75.375
2015-01-01	75.825
2016-01-01	75.900
2017-01-01	76.750