Year	Percent
1999-01-01	19.450
2000-01-01	20.050
2001-01-01	20.100
2002-01-01	20.400
2003-01-01	20.500
2004-01-01	19.875
2005-01-01	20.175
2006-01-01	19.450
2007-01-01	19.925
2008-01-01	19.325
2009-01-01	19.775
2010-01-01	20.650
2011-01-01	20.750
2012-01-01	21.350
2013-01-01	21.875
2014-01-01	21.900
2015-01-01	21.550
2016-01-01	20.050
2017-01-01	21.125