Year	Percent
1998-01-01	9.275
1999-01-01	8.900
2000-01-01	8.250
2001-01-01	7.475
2002-01-01	7.025
2003-01-01	6.875
2004-01-01	6.400
2005-01-01	6.275
2006-01-01	5.525
2007-01-01	4.975
2008-01-01	5.600
2009-01-01	6.825
2010-01-01	7.600
2011-01-01	7.650
2012-01-01	9.975
2013-01-01	11.700
2014-01-01	12.150
2015-01-01	11.575
2016-01-01	11.150
2017-01-01	10.600