Frequencies for first 10,000 rows of dechal variable in drug2005q3 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,892       88.92       88.92
          D |        619        6.19       95.11
          N |         86        0.86       95.97
          U |        196        1.96       97.93
          Y |        207        2.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Dec 2015