Year	Percent
1998-01-01	22.425
1999-01-01	22.550
2000-01-01	22.550
2001-01-01	23.050
2002-01-01	22.800
2003-01-01	22.300
2004-01-01	21.700
2005-01-01	21.625
2006-01-01	21.475
2007-01-01	21.650
2008-01-01	21.550
2009-01-01	21.475
2010-01-01	21.650
2011-01-01	22.775
2012-01-01	23.125
2013-01-01	23.125
2014-01-01	23.950
2015-01-01	24.150
2016-01-01	23.850
2017-01-01	23.575