Frequencies for first 10,000 rows of op_tocol variable in natlterr2011 dataset :

  Tocolysis |
        RFP |
602=f_ob_to |
       co R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      2,536       25.36       25.36
          N |      6,131       61.31       86.67
          U |      1,142       11.42       98.09
          Y |        191        1.91      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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