Year	Percent
1989-01-01	13.2
1993-01-01	15.5
1995-01-01	14.1
1996-01-01	14.1
1997-01-01	13.6
1998-01-01	13.1
1999-01-01	12.2
2000-01-01	11.6
2001-01-01	11.9
2002-01-01	12.3
2003-01-01	12.7
2004-01-01	13.0
2005-01-01	13.4
2006-01-01	13.4
2007-01-01	13.0
2008-01-01	13.3
2009-01-01	14.4
2010-01-01	15.4
2011-01-01	16.0
2012-01-01	16.0
2013-01-01	15.9
2014-01-01	15.6
2015-01-01	14.8
2016-01-01	14.1