各季人數 (14475)

E2=SUMPRODUCT(N(MMULT(N(MONTH($B$2:$B$16)<ROW(A1)*3-{3,0}+1),{1;1})=1))

F2=SUMPRODUCT((MONTH($B$2:$B$16)>ROW(A1)*3-3)*(MONTH($B$2:$B$16)<=ROW(A1)*3))

G2=SUMPRODUCT(N(INT((MONTH(B$2:B$16)-1)/3)+1=ROW(A1)))

A2=INT((MONTH(B2)-1)/3)+1