Frequencies for first 10,000 rows of dechal variable in drug2011q1 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,930       99.30       99.30
          D |         17        0.17       99.47
          N |         10        0.10       99.57
          U |         13        0.13       99.70
          Y |         30        0.30      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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