Frequencies for first 10,000 rows of opthmlgy_srgry_sw variable in pos2009 dataset :

      SPEC: |
OPTHAMOLOGY |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,644       96.44       96.44
          N |        148        1.48       97.92
          Y |        208        2.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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