Frequencies for first 10,000 rows of tocol variable in natlterr1995 dataset :

  Tocolysis |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        174        1.74        1.74
          2 |      9,818       98.18       99.92
          9 |          8        0.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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