Frequencies for first 10,000 rows of opthmlgy_srgry_sw variable in pos1998 dataset :

      spec: |
opthamology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,416       94.16       94.16
          N |        270        2.70       96.86
          Y |        314        3.14      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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