Year	Percent
1998-01-01	11.80
1999-01-01	12.75
2000-01-01	13.30
2001-01-01	13.70
2002-01-01	14.05
2003-01-01	14.20
2004-01-01	14.40
2005-01-01	14.60
2006-01-01	14.70
2007-01-01	13.85
2008-01-01	14.45
2009-01-01	16.05
2010-01-01	16.10
2011-01-01	16.03
2012-01-01	16.85
2013-01-01	16.60
2014-01-01	16.66
2015-01-01	16.95