Frequencies for first 10,000 rows of opthmlgy_srgry_sw variable in pos1995 dataset :

      spec: |
opthamology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,552       95.52       95.52
          N |        187        1.87       97.39
          Y |        261        2.61      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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