Frequencies for first 10,000 rows of dechal variable in drug2012q2 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,985       99.85       99.85
          D |          8        0.08       99.93
          N |          1        0.01       99.94
          Y |          6        0.06      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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