Year	Percent
1998-01-01	43.900
1999-01-01	43.650
2000-01-01	43.800
2001-01-01	44.375
2002-01-01	43.700
2003-01-01	43.000
2004-01-01	42.075
2005-01-01	41.825
2006-01-01	41.450
2007-01-01	41.375
2008-01-01	41.100
2009-01-01	40.350
2010-01-01	40.025
2011-01-01	40.700
2012-01-01	40.800
2013-01-01	40.875
2014-01-01	40.950
2015-01-01	40.625
2016-01-01	40.350
2017-01-01	40.425