Frequencies for first 10,000 rows of dechal variable in drug2007q2 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,824       98.24       98.24
          D |        101        1.01       99.25
          N |         16        0.16       99.41
          U |         41        0.41       99.82
          Y |         18        0.18      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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