Year	Percent
1998-01-01	38.075
1999-01-01	40.600
2000-01-01	40.750
2001-01-01	40.300
2002-01-01	42.300
2003-01-01	42.450
2004-01-01	42.450
2005-01-01	43.600
2006-01-01	42.850
2007-01-01	44.250
2008-01-01	43.975
2009-01-01	42.800
2010-01-01	43.800
2011-01-01	42.025
2012-01-01	41.950
2013-01-01	40.975
2014-01-01	42.050
2015-01-01	44.550
2016-01-01	46.350
2017-01-01	50.200