Year	Percent
1998-01-01	22.975
1999-01-01	20.600
2000-01-01	20.975
2001-01-01	19.325
2002-01-01	20.825
2003-01-01	21.700
2004-01-01	21.875
2005-01-01	20.325
2006-01-01	18.775
2007-01-01	16.400
2008-01-01	16.800
2009-01-01	23.600
2010-01-01	23.525
2011-01-01	21.400
2012-01-01	19.775
2013-01-01	22.575
2014-01-01	22.600
2015-01-01	24.775
2016-01-01	21.500
2017-01-01	20.600