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

Stimulation |
   of labor |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        860        8.60        8.60
          2 |      9,110       91.10       99.70
          9 |         30        0.30      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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