Frequencies for first 10,000 rows of forcep variable in natlterr1997 dataset :

    Forceps |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         48        0.48        0.48
          2 |      9,951       99.51       99.99
          9 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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