Frequencies for first 10,000 rows of rechal variable in drug2005q3 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,918       89.18       89.18
          D |        869        8.69       97.87
          N |         15        0.15       98.02
          U |        161        1.61       99.63
          Y |         37        0.37      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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