Year	Percent
1983-01-01	7.0
1984-01-01	7.3
1985-01-01	7.0
1986-01-01	6.6
1987-01-01	6.6
1988-01-01	6.9
1989-01-01	6.7
1990-01-01	6.3
1991-01-01	6.9
1992-01-01	7.8
1993-01-01	8.6
1994-01-01	8.9
1995-01-01	9.1
1996-01-01	9.7
1997-01-01	9.6
1998-01-01	10.9
1999-01-01	12.0
2000-01-01	11.2
2001-01-01	10.7
2002-01-01	10.3
2003-01-01	9.8
2004-01-01	10.5
2005-01-01	9.9
2006-01-01	8.9
2007-01-01	8.3
2008-01-01	7.7
2009-01-01	9.5
2010-01-01	12.6
2011-01-01	17.7