Year	Percent
1998-01-01	69.800
1999-01-01	67.850
2000-01-01	67.225
2001-01-01	67.325
2002-01-01	68.075
2003-01-01	67.375
2004-01-01	66.700
2005-01-01	67.575
2006-01-01	67.950
2007-01-01	69.125
2008-01-01	69.475
2009-01-01	67.950
2010-01-01	67.325
2011-01-01	67.425
2012-01-01	67.525
2013-01-01	68.125
2014-01-01	68.850
2015-01-01	69.375
2016-01-01	70.625
2017-01-01	71.675