1991 6.3 1992 6.8 1993 6.2 1994 5.5 1995 6.3 1996 6.6 1997 6.8 1998 5.3 1999 6.6 2000 7.6 2001 4.9 2002 7.4 2003 5.5 2004 6.3 2005 6.1 2006 5.1 2007 7.6 2008 5.9 2009 6.8