同年份 不重複客户數 (8972)

G2{=COUNT(0/(MATCH(A$2:A$11&F2,A$2:A$11&B$2:B$11,)=ROW($1:$10)))

另解=SUMPRODUCT((F2=B$2:B$11)/COUNTIFS(A:A,A$2:A$11,B:B,B$2:B$11))