Frequencies for first 10,000 rows of thorc_srgry_sw variable in pos1997 dataset :

      spec: |
   thoracic |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,456       94.56       94.56
          N |        516        5.16       99.72
          Y |         28        0.28      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 17 May 2017