data ia.percent1;
   if _n_ = 1 then set ia.summary (keep = CargoSum);
   set ia.monthsum (keep = SaleMon RevCargo);
   PctRev = RevCargo / CargoSum;
run;

proc print data = ia.percent1(drop=CargoSum);
   title 'Summary and Detailed Data Combined Using';
   title2 'PROC MEANS to Create the Summary';
run;