Year	Percent
1998-01-01	18.125
1999-01-01	18.050
2000-01-01	18.225
2001-01-01	18.200
2002-01-01	18.500
2003-01-01	19.000
2004-01-01	19.100
2005-01-01	18.400
2006-01-01	18.750
2007-01-01	19.700
2008-01-01	20.425
2009-01-01	20.125
2010-01-01	20.225
2011-01-01	19.575
2012-01-01	19.100
2013-01-01	18.050
2014-01-01	18.450
2015-01-01	18.575
2016-01-01	17.950
2017-01-01	17.875