Frequencies for first 10,000 rows of primac variable in natlterr1998 dataset :

    Primary |
  C-section |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      2,030       20.30       20.30
          2 |      7,968       79.68       99.98
          9 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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