Frequencies for first 10,000 rows of tocol variable in natlterr1996 dataset :

  Tocolysis |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        271        2.71        2.71
          2 |      9,724       97.24       99.95
          9 |          5        0.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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