Frequencies for first 10,000 rows of primac variable in natl1991 dataset :

    Primary |
  C-section |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,627       16.27       16.27
          2 |      8,357       83.57       99.84
          9 |         16        0.16      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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