Frequencies for first 10,000 rows of tocol variable in natl1995 dataset :

  Tocolysis |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        122        1.22        1.22
          2 |      9,851       98.51       99.73
          9 |         27        0.27      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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