Year Annual Number 1970 26 1971 0 1972 100 1973 0 1974 0 1975 47 1976 0 1977 0 1978 0 1979 0 1980 61 1981 212 1982 0 1983 0 1984 10920 1985 0 1986 36 1987 0 1988 20000000 1989 0 1990 0 1991 55880 1992 0 1993 40270 1994 0 1995 0 1996 0 1997 156500 1998 0 1999 478000 2000 0 2001 6342000 2002 202 2003 0 2004 0 2005 157900 2006 0 2007 0 2008 0