Frequencies for first 10,000 rows of dechal variable in drug2007q4 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,642       96.42       96.42
          D |        211        2.11       98.53
          N |         28        0.28       98.81
          U |         64        0.64       99.45
          Y |         55        0.55      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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