Frequencies for first 10,000 rows of forcep variable in natl1997 dataset :

    Forceps |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        592        5.92        5.92
          2 |      9,397       93.97       99.89
          9 |         11        0.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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