Year	Percent
1998-01-01	11.7
1999-01-01	11.6
2000-01-01	13.3
2001-01-01	10.6
2002-01-01	9.8
2003-01-01	9.3
2004-01-01	11.6
2005-01-01	12.4
2006-01-01	12.4
2007-01-01	12.4
2008-01-01	12.4
2009-01-01	12.2
2010-01-01	11.6
2011-01-01	11.9
2012-01-01	11.8
2013-01-01	8.2
2014-01-01	9.4
2015-01-01	12.1