Year	Percent
1998-01-01	11.6
1999-01-01	12.2
2000-01-01	13.5
2001-01-01	14.3
2002-01-01	16.1
2003-01-01	15.3
2004-01-01	14.9
2005-01-01	14.6
2006-01-01	13.3
2007-01-01	12.6
2008-01-01	13.7
2009-01-01	13.3
2010-01-01	11.9
2011-01-01	12.3
2012-01-01	12.6
2013-01-01	12.7
2014-01-01	12.3
2015-01-01	12.7