Frequencies for first 10,000 rows of forcep variable in natl1993 dataset :

    Forceps |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        750        7.50        7.50
          2 |      9,240       92.40       99.90
          9 |         10        0.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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