Year	Percent
1998-01-01	43.600
1999-01-01	43.100
2000-01-01	42.250
2001-01-01	41.500
2002-01-01	40.725
2003-01-01	40.125
2004-01-01	39.925
2005-01-01	38.975
2006-01-01	38.600
2007-01-01	38.000
2008-01-01	37.950
2009-01-01	37.900
2010-01-01	37.375
2011-01-01	38.200
2012-01-01	38.025
2013-01-01	38.350
2014-01-01	38.400
2015-01-01	38.250
2016-01-01	38.425
2017-01-01	37.700