Source data comes from the circulation statements each year, as follows:

   * January 1961 (page 116): 48,018
   * January 1962 (page 136): 51,110
   * January 1963 (page 60): 52,301
   * January 1964 (page 96): 43,929
   * January 1965 (page 64): 35,471
   * January 1966 (page 124): 46,319
   * February 1967 (page 12): 47,958
   * 1968 (Locus #155): 40,343
   * February 1969 (page 47): 38,551
   * 1970 (Locus #155): 34,791
   * March 1971 (page 61): 30,298
   * March 1972 (page 130): 28,500
   * March 1973 (page 93): 27,402
   * February 1974 (page 67): 26,577
   * March 1975 (page 91): 23,631
   * May 1975 (page 69): 24,091 (Revised?)
   * March 1976 (page 83): 22,825
   * March 1977 (page 61): 24,800
   * May 1978 (page 81): 25,700
   * May 1979 (page 129): 22,784
   * May 1980 (page 126): 22,332
   * March 1981 (page 71): 17,339
   * 1982 (Locus # 265): 17,784
   * 1983 (Locus # 265): 11,500
   * May 1984 (page 70): 11,286
   * May 1985 (page 101): 10,930
   * March 1986 (page 161): 12,323
   * May 1987 (page 161): 13,183
   * May 1988 (page 96): 13,677
   * March 1989 (page 37): 14,895
   * May 1990 (page 10): 12,638
   * May 1991 (page 60): 15,702
   * January 1993 (page 93): 6,466
   * Winter 1994 (page 52): 7,851 

Note that the data does not come from a calendar year. The statements were each sworn on October 1 of the preceding year. The circulation figures could take two or three months to come in, since it was necessary to wait for returns from news stands to know what the paid circulation was. Hence information printed in May 1979 might actually relate to the twelve-month period from February 1978 to January 1979. The data has hence been attributed to the previous year in the graph.

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