Frequencies for first 10,000 rows of prov1960 variable in pos1995 dataset :

       330e |
 toxicology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,884       88.84       88.84
          N |        879        8.79       97.63
          Y |        237        2.37      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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