Year	Percent
1998-01-01	20.675
1999-01-01	21.275
2000-01-01	22.175
2001-01-01	22.125
2002-01-01	21.225
2003-01-01	20.650
2004-01-01	23.100
2005-01-01	20.800
2006-01-01	20.025
2007-01-01	19.500
2008-01-01	19.200
2009-01-01	16.900
2010-01-01	16.325
2011-01-01	15.475
2012-01-01	15.000
2013-01-01	13.725
2014-01-01	12.750
2015-01-01	12.450
2016-01-01	13.725
2017-01-01	13.875