proc datasets lib=ia;
   modify year2000 (genmax=4);
run;

data ia.year2000;
   set ia.year2000 
       ia.quarter2 (drop=Comment);
run;

data ia.year2000;
   set ia.year2000 
       ia.quarter3 (drop=Comment);
run;

data ia.year2000;
   set ia.year2000 
       ia.quarter4 (drop=Comment);
run;

proc sort data = ia.year2000;
   by Date;
run;