Frequencies for first 10,000 rows of tocol variable in natl1999 dataset :

  Tocolysis |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        155        1.55        1.55
          2 |      9,845       98.45      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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