Frequencies for first 10,000 rows of primac variable in natlterr2000 dataset :

    Primary |
  C-section |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      2,355       23.55       23.55
          2 |      7,644       76.44       99.99
          9 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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