Frequencies for first 10,000 rows of opthmlgy_srgry_sw variable in pos2000 dataset :

      spec: |
opthamology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,327       93.27       93.27
          N |        330        3.30       96.57
          Y |        343        3.43      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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