Frequencies for first 10,000 rows of dechal variable in drug2007q1 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,572       95.72       95.72
          D |        236        2.36       98.08
          N |         39        0.39       98.47
          U |         64        0.64       99.11
          Y |         89        0.89      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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