Year	Percent
1998-01-01	8.5
1999-01-01	7.9
2000-01-01	7.0
2001-01-01	6.6
2002-01-01	6.2
2003-01-01	6.4
2004-01-01	7.2
2005-01-01	8.2
2006-01-01	10.7
2007-01-01	11.3
2008-01-01	12.9
2009-01-01	13
2010-01-01	13.1
2011-01-01	13.1
2012-01-01	13.3
2013-01-01	12.9
2014-01-01	12.5
2015-01-01	12.7