Frequencies for first 10,000 rows of opthmlgy_srgry_sw variable in pos2006 dataset :

      spec: |
opthamology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,531       95.31       95.31
          N |        169        1.69       97.00
          Y |        300        3.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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