Year	Percent
1999-01-01	49.250
2000-01-01	49.975
2001-01-01	49.750
2002-01-01	49.850
2003-01-01	50.650
2004-01-01	50.500
2005-01-01	50.525
2006-01-01	50.900
2007-01-01	50.650
2008-01-01	50.050
2009-01-01	48.800
2010-01-01	48.725
2011-01-01	49.125
2012-01-01	50.125
2013-01-01	51.150
2014-01-01	54.150
2015-01-01	55.850
2016-01-01	57.950
2017-01-01	59.275