Frequencies for first 10,000 rows of dechal variable in drug2015q2 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,960       99.60       99.60
          D |         20        0.20       99.80
          N |          3        0.03       99.83
          U |         16        0.16       99.99
          Y |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 19 Apr 2017