Year	Percent
1998-01-01	69.100
1999-01-01	71.075
2000-01-01	71.875
2001-01-01	72.450
2002-01-01	72.825
2003-01-01	72.175
2004-01-01	72.025
2005-01-01	72.850
2006-01-01	73.275
2007-01-01	73.825
2008-01-01	73.950
2009-01-01	73.525
2010-01-01	72.475
2011-01-01	72.650
2012-01-01	73.425
2013-01-01	73.425
2014-01-01	73.900
2015-01-01	74.450
2016-01-01	74.075
2017-01-01	74.900