Frequencies for first 10,000 rows of prov2290 variable in pos1993 dataset :

      spec: |
opthamology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,608       96.08       96.08
          N |        155        1.55       97.63
          Y |        237        2.37      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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