Year	Percent
1998-01-01	7.400
1999-01-01	8.075
2000-01-01	7.475
2001-01-01	7.250
2002-01-01	6.775
2003-01-01	6.225
2004-01-01	6.650
2005-01-01	6.200
2006-01-01	5.700
2007-01-01	5.250
2008-01-01	5.125
2009-01-01	6.975
2010-01-01	10.075
2011-01-01	15.175
2012-01-01	21.575
2013-01-01	24.525
2014-01-01	23.650
2015-01-01	21.750
2016-01-01	19.875
2017-01-01	17.850