1968 1969a 1969b 1970 1971a
1971b 1971c 1972 1974 1975a
1975b 1975c 1976a 1976b 1977a
1977b 1977c 1978a 1978b 1978c
1978d 1978e 1978f 1979 1980
1982a 1982b 1982c  1982d 1983
1984 1985 1986a 1986b 1987
1988 1989