Frequencies for first 10,000 rows of dechal variable in drug2010q1 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,800       98.00       98.00
          D |         76        0.76       98.76
          N |         28        0.28       99.04
          U |         13        0.13       99.17
          Y |         83        0.83      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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