Year	Percent
1998-01-01	70.075
1999-01-01	69.900
2000-01-01	70.100
2001-01-01	70.375
2002-01-01	70.625
2003-01-01	70.125
2004-01-01	69.450
2005-01-01	69.100
2006-01-01	69.275
2007-01-01	69.150
2008-01-01	68.950
2009-01-01	67.700
2010-01-01	67.200
2011-01-01	67.075
2012-01-01	66.300
2013-01-01	65.125
2014-01-01	64.525
2015-01-01	64.125
2016-01-01	64.100
2017-01-01	64.550