Frequencies for first 10,000 rows of rechal variable in drug2015q2 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |        177        1.77        1.77
          D |      8,522       85.22       86.99
          N |        216        2.16       89.15
          U |      1,038       10.38       99.53
          Y |         47        0.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 19 Apr 2017