Year Annual Number 1970 0 1971 0 1972 0 1973 517 1974 0 1975 0 1976 0 1977 0 1978 3859 1979 7540 1980 6427 1981 31 1982 26 1983 0 1984 0 1985 2140000 1986 0 1987 3052 1988 0 1989 353 1990 0 1991 0 1992 0 1993 0 1994 0 1995 67200 1996 0 1997 17000 1998 0 1999 138000 2000 1 2001 0 2002 0 2003 178600 2004 0 2005 0 2006 0 2007 0 2008 0