Frequencies for first 10,000 rows of uop_stiml variable in natl2006 dataset :

Stimulation |
 of labor U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,450       14.50       14.50
          2 |      8,416       84.16       98.66
          9 |        134        1.34      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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