Year	Percent
1999-01-01	27.650
2000-01-01	27.225
2001-01-01	28.850
2002-01-01	27.575
2003-01-01	26.425
2004-01-01	25.275
2005-01-01	23.200
2006-01-01	23.050
2007-01-01	21.925
2008-01-01	21.000
2009-01-01	20.750
2010-01-01	19.575
2011-01-01	21.275
2012-01-01	20.875
2013-01-01	20.250
2014-01-01	19.450
2015-01-01	19.800
2016-01-01	20.150
2017-01-01	20.400