March 21 – June 20 1968
June 21 – September 20 1968
September 21 – December 20 1968
December 21 1968 – March 20 1969
March 21 – June 20 1969
June 21 – September 20 1969
September 21 – December 20 1969
December 21 1969 – March 20 1970
March 21 – June 20 1970
June 21 – September 20 1970
September 21 – December 20 1970
December 21 1970 – March 20 1971
March 21 – September 20 1971
September 21 – December 20 1971
December 21 1971 – March 20 1972
March 21 – June 20 1972