Frequencies for first 10,000 rows of forcep variable in natl2002 dataset :

    Forceps |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        109        1.09        1.09
          2 |      9,870       98.70       99.79
          9 |         21        0.21      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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