Frequencies for first 10,000 rows of prov2020 variable in pos1993 dataset :

        900 |
cytogenetic |
          s |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,797       87.97       87.97
          N |      1,189       11.89       99.86
          Y |         14        0.14      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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