Year	Percent
1998-01-01	64.050
1999-01-01	66.275
2000-01-01	67.150
2001-01-01	68.125
2002-01-01	68.075
2003-01-01	67.700
2004-01-01	67.650
2005-01-01	68.375
2006-01-01	69.350
2007-01-01	70.300
2008-01-01	71.050
2009-01-01	68.725
2010-01-01	68.150
2011-01-01	69.025
2012-01-01	69.375
2013-01-01	68.875
2014-01-01	68.725
2015-01-01	68.550
2016-01-01	69.075
2017-01-01	69.975