Frequencies for first 10,000 rows of op_tocol variable in linkpe2009psden dataset :

Tocolysis R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      3,422       34.22       34.22
          N |      6,458       64.58       98.80
          U |          1        0.01       98.81
          Y |        119        1.19      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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