Year	Percent
1998-01-01	9.200
1999-01-01	10.225
2000-01-01	9.775
2001-01-01	9.325
2002-01-01	9.150
2003-01-01	8.775
2004-01-01	9.525
2005-01-01	9.175
2006-01-01	8.200
2007-01-01	7.825
2008-01-01	7.225
2009-01-01	9.050
2010-01-01	12.125
2011-01-01	17.225
2012-01-01	23.750
2013-01-01	26.900
2014-01-01	26.025
2015-01-01	24.450
2016-01-01	22.800
2017-01-01	20.725