Year	Percent
1999-01-01	28.800
2000-01-01	28.975
2001-01-01	29.025
2002-01-01	28.375
2003-01-01	27.950
2004-01-01	29.600
2005-01-01	28.550
2006-01-01	27.625
2007-01-01	26.500
2008-01-01	26.125
2009-01-01	25.675
2010-01-01	25.575
2011-01-01	25.450
2012-01-01	24.900
2013-01-01	24.500
2014-01-01	24.600
2015-01-01	24.475
2016-01-01	23.800
2017-01-01	23.575