Frequencies for first 10,000 rows of prov1960 variable in pos1994 dataset :

       330e |
 toxicology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,798       87.98       87.98
          N |        949        9.49       97.47
          Y |        253        2.53      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 17 May 2017