Year Annual Number 1970 0 1971 0 1972 0 1973 0 1974 0 1975 0 1976 5016000 1977 0 1978 0 1979 2040 1980 0 1981 0 1982 20 1983 0 1984 0 1985 5000 1986 2500 1987 0 1988 2055 1989 0 1990 0 1991 23900 1992 0 1993 0 1994 0 1995 0 1996 0 1997 0 1998 0 1999 282 2000 0 2001 158 2002 0 2003 0 2004 0 2005 0 2006 0 2007 0 2008 0