Frequencies for first 10,000 rows of dechal variable in drug2005q4 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,595       85.95       85.95
          D |        790        7.90       93.85
          N |         96        0.96       94.81
          U |        244        2.44       97.25
          Y |        275        2.75      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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