Year	Percent
1998-01-01	24.775
1999-01-01	21.675
2000-01-01	21.275
2001-01-01	19.500
2002-01-01	20.525
2003-01-01	21.200
2004-01-01	18.900
2005-01-01	19.225
2006-01-01	18.125
2007-01-01	16.475
2008-01-01	15.525
2009-01-01	18.500
2010-01-01	18.700
2011-01-01	18.150
2012-01-01	17.825
2013-01-01	16.725
2014-01-01	18.150
2015-01-01	19.425
2016-01-01	18.275
2017-01-01	18.975