Year Percent 1992 27.35172 1993 19.43513 1994 21.91317 1995 18.81167 1996 16.22737 1997 15.11534 1998 23.36709 1999 22.72234 2000 12.59042 2001 15.16384 2002 13.60181 2003 11.82992 2004 10.64227 2005 22.6 2006 24.6 2007 24.26598 2008 16.77631 2009 14.12423