Year	Percent
1998-01-01	66.825
1999-01-01	67.525
2000-01-01	68.375
2001-01-01	69.000
2002-01-01	68.775
2003-01-01	68.000
2004-01-01	67.650
2005-01-01	67.300
2006-01-01	67.625
2007-01-01	67.600
2008-01-01	68.025
2009-01-01	66.075
2010-01-01	65.275
2011-01-01	63.825
2012-01-01	61.425
2013-01-01	60.625
2014-01-01	62.625
2015-01-01	63.925
2016-01-01	65.250
2017-01-01	67.825