Year	Percent
1998-01-01	70.625
1999-01-01	70.900
2000-01-01	71.450
2001-01-01	72.050
2002-01-01	72.650
2003-01-01	72.825
2004-01-01	72.725
2005-01-01	73.200
2006-01-01	73.600
2007-01-01	73.875
2008-01-01	73.975
2009-01-01	73.400
2010-01-01	73.675
2011-01-01	73.625
2012-01-01	73.425
2013-01-01	73.050
2014-01-01	73.250
2015-01-01	73.400
2016-01-01	73.700
2017-01-01	74.675