1983 10.9% 1984 15.2% 1985 13.5% 1986 8.8% 1987 11.6% 1988 11.3% 1989 4.1% 1990 3.8% 1991 9.2% 1992 14.2% 1993 14.0% 1994 13.1% 1995 10.9% 1996 10.0% 1997 9.3% 1998 7.8% 1999 7.6% 2000 8.4% 2001 8.3% 2002 9.1% 2003 10.0% 2004 10.1% 2005 10.4% 2006 10.7% 2007 11.9 %。