Survey 17 - May 1978

Survey 16 - November 1977

Survey 15 - August 1976

Survey 14 - February 1976

Survey 13 - July 1975

Survey 12 - September 1974

Survey 11 - July 1974

Survey 10 - January 1974

Survey 9 - September 1973

Survey 8 - July 1973

Survey 7 - May 1973

Survey 6 - December 1972

Survey 5 - August 1972

Survey 4 - May 1972

Survey 3 - November 1971

Survey 2 - July 1971

Survey 1 - February 1971