Frequencies for first 10,000 rows of prov2020 variable in pos1995 dataset :

        900 |
cytogenetic |
          s |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,884       88.84       88.84
          N |      1,102       11.02       99.86
          Y |         14        0.14      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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