Year	Percent
1998-01-01	75.875
1999-01-01	75.825
2000-01-01	76.550
2001-01-01	76.975
2002-01-01	76.550
2003-01-01	74.925
2004-01-01	74.025
2005-01-01	73.275
2006-01-01	73.700
2007-01-01	73.650
2008-01-01	73.800
2009-01-01	70.850
2010-01-01	69.725
2011-01-01	67.725
2012-01-01	64.500
2013-01-01	63.475
2014-01-01	65.775
2015-01-01	66.875
2016-01-01	68.250
2017-01-01	71.100