Year	Percent
1998-01-01	75.950
1999-01-01	74.000
2000-01-01	73.150
2001-01-01	73.175
2002-01-01	73.875
2003-01-01	73.100
2004-01-01	72.325
2005-01-01	73.275
2006-01-01	73.675
2007-01-01	74.825
2008-01-01	75.425
2009-01-01	73.850
2010-01-01	73.525
2011-01-01	74.025
2012-01-01	74.625
2013-01-01	75.650
2014-01-01	77.000
2015-01-01	77.875
2016-01-01	79.300
2017-01-01	80.875