Year	Percent
1991-01-01	6.1
1992-01-01	6.8
1993-01-01	6.9
1994-01-01	6.7
1995-01-01	6.4
1996-01-01	6.5
1997-01-01	6.2
1998-01-01	6.0
1999-01-01	5.9
2000-01-01	5.4
2001-01-01	5.8
2002-01-01	6.4
2003-01-01	6.7
2004-01-01	6.4
2005-01-01	6.1
2006-01-01	5.7
2007-01-01	5.3
2008-01-01	5.9
2009-01-01	8.5
2010-01-01	8.6
2011-01-01	7.8
2012-01-01	7.5
2013-01-01	7.3
2014-01-01	6.5
2015-01-01	6.0
2016-01-01	5.6