Frequencies for first 10,000 rows of rechal variable in drug2013q2 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |        689        6.89        6.89
          D |      7,639       76.39       83.28
          N |        221        2.21       85.49
          U |      1,409       14.09       99.58
          Y |         42        0.42      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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