Year	Percent
1999-01-01	56.500
2000-01-01	54.800
2001-01-01	55.800
2002-01-01	53.025
2003-01-01	51.150
2004-01-01	49.600
2005-01-01	48.175
2006-01-01	46.375
2007-01-01	45.025
2008-01-01	43.450
2009-01-01	42.050
2010-01-01	41.050
2011-01-01	40.150
2012-01-01	39.375
2013-01-01	39.350
2014-01-01	39.725
2015-01-01	39.675
2016-01-01	39.700
2017-01-01	40.225