Year	Percent
1999-01-01	67.575
2000-01-01	67.850
2001-01-01	67.250
2002-01-01	67.100
2003-01-01	67.600
2004-01-01	67.250
2005-01-01	67.925
2006-01-01	68.900
2007-01-01	68.650
2008-01-01	67.975
2009-01-01	67.725
2010-01-01	67.775
2011-01-01	68.375
2012-01-01	69.575
2013-01-01	71.000
2014-01-01	73.425
2015-01-01	75.275
2016-01-01	76.950
2017-01-01	78.250