Frequencies for first 10,000 rows of opthmlgy_srgry_sw variable in pos1994 dataset :

      spec: |
opthamology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,575       95.75       95.75
          N |        173        1.73       97.48
          Y |        252        2.52      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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