Frequencies for first 10,000 rows of op_tocol variable in natlterr2010 dataset :

  Tocolysis |
        RFP |
602=f_ob_to |
       co R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      4,656       46.56       46.56
          N |      4,228       42.28       88.84
          U |      1,010       10.10       98.94
          Y |        106        1.06      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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