proc import out=test
datafile="d:\test1.csv"
dbms=csv replace;
getnames=yes;
run;
data a;
set test;
by stkcd year;
if last.year ;
sum+earning;
sum_1=sum-earning;
run;
data b;
merge a a(firstobs=3 drop=sum_1 earning rename=(sum=sum_2)) ;
ma=(sum_2-sum_1);
run;