Frequencies for first 10,000 rows of prov2010 variable in pos1991 dataset :

        630 |
   cytology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,536       85.36       85.36
          N |      1,076       10.76       96.12
          Y |        388        3.88      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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