Year	Percent
1999-01-01	23.100
2000-01-01	23.250
2001-01-01	22.625
2002-01-01	23.275
2003-01-01	23.275
2004-01-01	23.450
2005-01-01	23.525
2006-01-01	23.600
2007-01-01	24.050
2008-01-01	23.650
2009-01-01	23.725
2010-01-01	23.950
2011-01-01	23.425
2012-01-01	22.850
2013-01-01	22.775
2014-01-01	22.400
2015-01-01	22.525
2016-01-01	21.750
2017-01-01	21.775