Frequencies for first 10,000 rows of prov2290 variable in pos1996 dataset :

      spec: |
opthamology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,497       94.97       94.97
          N |        223        2.23       97.20
          Y |        280        2.80      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 26 Jan 2016