Frequencies for first 10,000 rows of rechal variable in drug2017q4 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,412       84.12       84.12
          N |        160        1.60       85.72
          U |      1,415       14.15       99.87
          Y |         13        0.13      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 19 Jun 2018