Frequencies for first 10,000 rows of tocol variable in natlterr2000 dataset :

  Tocolysis |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        250        2.50        2.50
          2 |      9,744       97.44       99.94
          9 |          6        0.06      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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