Year	Percent
1999-01-01	45.975
2000-01-01	46.575
2001-01-01	46.200
2002-01-01	46.200
2003-01-01	46.850
2004-01-01	46.650
2005-01-01	46.575
2006-01-01	46.850
2007-01-01	46.575
2008-01-01	46.000
2009-01-01	44.850
2010-01-01	44.750
2011-01-01	45.100
2012-01-01	45.950
2013-01-01	46.875
2014-01-01	49.525
2015-01-01	51.025
2016-01-01	52.850
2017-01-01	53.925