Year	Percent
1998-01-01	24.425
1999-01-01	23.325
2000-01-01	22.825
2001-01-01	22.425
2002-01-01	22.950
2003-01-01	23.200
2004-01-01	23.525
2005-01-01	23.400
2006-01-01	22.875
2007-01-01	22.775
2008-01-01	22.050
2009-01-01	23.600
2010-01-01	23.575
2011-01-01	22.800
2012-01-01	22.925
2013-01-01	23.175
2014-01-01	23.175
2015-01-01	22.825
2016-01-01	22.275
2017-01-01	21.475