Frequencies for first 10,000 rows of stimula variable in linkco1991us_num dataset :

Stimulation |
   of labor |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        579        5.79        5.79
          2 |      9,210       92.10       97.89
          9 |        211        2.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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