Year	Percent
1987-12-31	7.03
1988-12-31	9.08
1989-12-31	8.39
1990-12-31	7.53
1991-12-31	4.21
1992-12-31	3.21
1993-12-31	3.16
1994-12-31	5.9
1995-12-31	5.6
1996-12-31	5.42
1997-12-31	5.61
1998-12-31	4.98
1999-12-31	5.75
2000-12-31	6.5
2001-12-31	1.81
2002-12-31	1.32
2003-12-31	1.06
2004-12-31	2.33
2005-12-31	4.36
2006-12-31	5.3
2007-12-31	4.61
2008-12-31	0.45
2009-12-31	0.23
2010-12-31	0.33
2011-12-31	0.29
2012-12-31	0.21