Frequencies for first 10,000 rows of uop_tocol variable in natl2004 dataset :

  Tocolysis |
        U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        139        1.39        1.39
          2 |      9,201       92.01       93.40
          9 |        660        6.60      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 21 Jan 2016