proc sql;
create table shuju as
select SB,year,month,sum(mv) as mv,sum(fenzi) as fenzi,sum(fenzi)/sum(mv) as rp
from aa
group by 1,2,3;
quit;

与此帖类似：
https://bbs.pinggu.org/thread-6575726-1-1.html

里面的mv，fenzi，我随便编了一些数字，但大概按照你希望的business写了一下，你看看。
data work.test;
input sb $ year month mv fenzi;
datalines;
BH 2000 11 4 3
BH 2000 11 5 3
BH 2000 11 2 6
BH 2000 12 8 1
BH 2000 12 2 5
BH 2000 12 4 3
BH 2001 1 3 6
BH 2001 1 7 6
BH 2001 1 5 5
BL 2000 11 3 3
BL 2000 11 8 3
BL 2000 11 2 4
BL 2000 12 5 3
BL 2000 12 2 2
BL 2000 12 6 9
BL 2001 1 4 7
BL 2001 1 8 1
BL 2001 1 3 6
;
run;

proc sort data = work.test ;
by sb year month;
run;

data work.test1 (drop= mv fenzi mvsum fenzisum);
set work.test;
by sb year month;
if first.month then do;
mvsum = 0;
fenzisum = 0;
end;
mvsum + mv;
fenzisum + fenzi;
if last.month then do;
rp = fenzisum/mvsum;
output;
end;
run;

谢谢谢谢，十分感谢！