Frequencies for first 10,000 rows of stimula variable in natl1996 dataset :

Stimulation |
   of labor |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,347       13.47       13.47
          2 |      8,624       86.24       99.71
          9 |         29        0.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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