Frequencies for first 10,000 rows of prov1960 variable in pos1991 dataset :

       330e |
 toxicology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,536       85.36       85.36
          N |      1,324       13.24       98.60
          Y |        140        1.40      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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