Year	Percent
1998-01-01	15.975
1999-01-01	15.225
2000-01-01	15.100
2001-01-01	15.050
2002-01-01	14.550
2003-01-01	15.225
2004-01-01	15.450
2005-01-01	14.950
2006-01-01	14.750
2007-01-01	14.425
2008-01-01	14.100
2009-01-01	14.275
2010-01-01	15.575
2011-01-01	15.675
2012-01-01	15.900
2013-01-01	16.675
2014-01-01	16.400
2015-01-01	16.400
2016-01-01	17.250
2017-01-01	16.375