Frequencies for first 10,000 rows of dechal variable in drug2011q3 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,975       99.75       99.75
          D |         13        0.13       99.88
          N |          2        0.02       99.90
          Y |         10        0.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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