Year	Percent
1987-12-31	7.2
1988-12-31	9.14
1989-12-31	8.32
1990-12-31	7.52
1991-12-31	4.16
1992-12-31	3.28
1993-12-31	3.22
1994-12-31	6.16
1995-12-31	5.54
1996-12-31	5.44
1997-12-31	5.65
1998-12-31	4.98
1999-12-31	5.82
2000-12-31	6.43
2001-12-31	1.8
2002-12-31	1.32
2003-12-31	1.08
2004-12-31	2.43
2005-12-31	4.45
2006-12-31	5.31
2007-12-31	4.66
2008-12-31	1.12
2009-12-31	0.24
2010-12-31	0.35
2011-12-31	0.42
2012-12-31	0.26