Frequencies for first 10,000 rows of tocol variable in natl1994 dataset :

  Tocolysis |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        110        1.10        1.10
          2 |      9,873       98.73       99.83
          9 |         17        0.17      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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