Frequencies for first 10,000 rows of rechal variable in drug2004q4 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,792       87.92       87.92
          D |        872        8.72       96.64
          N |         18        0.18       96.82
          U |        282        2.82       99.64
          Y |         36        0.36      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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