Year	Percent
1998-01-01	56.000
1999-01-01	55.725
2000-01-01	55.225
2001-01-01	55.250
2002-01-01	55.900
2003-01-01	58.725
2004-01-01	56.400
2005-01-01	58.800
2006-01-01	59.175
2007-01-01	59.075
2008-01-01	59.200
2009-01-01	57.750
2010-01-01	56.575
2011-01-01	52.350
2012-01-01	47.675
2013-01-01	45.975
2014-01-01	43.975
2015-01-01	44.925
2016-01-01	46.200
2017-01-01	49.550