Frequencies for first 10,000 rows of primac variable in natl1992 dataset :

    Primary |
  C-section |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,598       15.98       15.98
          2 |      8,398       83.98       99.96
          9 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015