Frequencies for first 10,000 rows of rechal variable in drug2005q2 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      6,633       66.33       66.33
          D |      2,570       25.70       92.03
          N |         69        0.69       92.72
          U |        623        6.23       98.95
          Y |        105        1.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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