Frequencies for first 10,000 rows of primac variable in natl1996 dataset :

    Primary |
  C-section |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,481       14.81       14.81
          2 |      8,506       85.06       99.87
          9 |         13        0.13      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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