DATA a;

  INFILE 'oxford.dat';

  INPUT 
       YearBorn   AgeDied   X_ray   N_Cases   N_Ctls  ;
   
PROC PRINT;

DATA b (DROP = N_Cases N_Ctls);

  set a;

  Event = 1; Number = N_Cases;
  IF Number > 0 THEN OUTPUT;
  
  Event = 0; Number = N_Ctls;
  IF Number > 0 THEN OUTPUT;
  
PROC SORT; BY Event;

PROC MEANS;

  BY Event;
  FREQ Number;

RUN;