Year	Percent
1998-01-01	54.250
1999-01-01	57.400
2000-01-01	61.250
2001-01-01	66.800
2002-01-01	68.000
2003-01-01	73.000
2004-01-01	79.950
2005-01-01	73.250
2006-01-01	71.200
2007-01-01	67.300
2008-01-01	61.600
2009-01-01	57.950
2010-01-01	57.050
2011-01-01	56.850
2012-01-01	56.960
2013-01-01	56.400
2014-01-01	57.915
2015-01-01	57.720