Year	Percent
1982-01-01	7.8
1983-01-01	8.4
1984-01-01	7.9
1985-01-01	6.6
1986-01-01	5.0
1987-01-01	5.0
1988-01-01	5.7
1989-01-01	6.8
1990-01-01	7.2
1991-01-01	7.9
1992-01-01	8.6
1993-01-01	9.5
1994-01-01	7.7
1995-01-01	6.8
1996-01-01	6.3
1997-01-01	5.2
1998-01-01	4.9
1999-01-01	5.1
2000-01-01	4.3
2001-01-01	4.5
2002-01-01	4.6
2003-01-01	5.4
2004-01-01	5.5
2005-01-01	4.8
2006-01-01	3.9
2007-01-01	3.8
2008-01-01	3.4
2009-01-01	6.1
2010-01-01	7.5
2011-01-01	7.6