Year	Percent
1998-01-01	11.4
1999-01-01	11.6
2000-01-01	11.5
2001-01-01	11.2
2002-01-01	10.3
2003-01-01	10.7
2004-01-01	12.1
2005-01-01	13
2006-01-01	12.6
2007-01-01	12.3
2008-01-01	10.9
2009-01-01	11.4
2010-01-01	12.6
2011-01-01	12.4
2012-01-01	12.6
2013-01-01	12.2
2014-01-01	11.1
2015-01-01	11.1