Frequencies for first 10,000 rows of dechal variable in drug2009q3 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,864       98.64       98.64
          D |         53        0.53       99.17
          N |         25        0.25       99.42
          Y |         58        0.58      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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