Year	Percent
1999-01-01	23.150
2000-01-01	21.950
2001-01-01	23.425
2002-01-01	21.475
2003-01-01	20.050
2004-01-01	19.100
2005-01-01	18.800
2006-01-01	17.700
2007-01-01	16.875
2008-01-01	15.975
2009-01-01	15.175
2010-01-01	14.300
2011-01-01	13.800
2012-01-01	13.100
2013-01-01	12.850
2014-01-01	12.675
2015-01-01	12.650
2016-01-01	12.600
2017-01-01	12.975