Frequencies for first 10,000 rows of opthmlgy_srgry_sw variable in pos2005 dataset :

      spec: |
opthamology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,323       93.23       93.23
          N |        315        3.15       96.38
          Y |        362        3.62      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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