Frequencies for first 10,000 rows of primac variable in natlterr1999 dataset :

    Primary |
  C-section |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      2,291       22.91       22.91
          2 |      7,706       77.06       99.97
          9 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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