Frequencies for first 10,000 rows of stimula variable in natlterr1998 dataset :

Stimulation |
   of labor |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,675       16.75       16.75
          2 |      8,323       83.23       99.98
          9 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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