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

  Tocolysis |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         85        0.85        0.85
          2 |      9,886       98.86       99.71
          9 |         29        0.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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