Frequencies for first 10,000 rows of primac variable in natlterr1994 dataset :

    Primary |
  C-section |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,777       17.77       17.77
          2 |      8,223       82.23      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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