Frequencies for first 10,000 rows of primac variable in natl2000 dataset :

    Primary |
  C-section |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,612       16.12       16.12
          2 |      8,348       83.48       99.60
          9 |         40        0.40      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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