Frequencies for first 10,000 rows of opthmlgy_srgry_sw variable in pos2003 dataset :

      spec: |
opthamology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,140       91.40       91.40
          N |        463        4.63       96.03
          Y |        397        3.97      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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