Frequencies for first 10,000 rows of rechal variable in drug2008q2 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,696       86.96       86.96
          D |      1,099       10.99       97.95
          N |         22        0.22       98.17
          U |        139        1.39       99.56
          Y |         44        0.44      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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