在excel中如何设计一个系统自动统计各科前20名各班占的人数，请高手指点。

H1： =sumproduct ((A$2:A$100=G2)*(D$2:D$100>=-small(-D$2:D$100,20))-(countif(D$2:D$100,">="&-small(-D$2:D$100,20)-20))/countif(D$2:D$100,"="&-small(-D$2:D$100,20))*sumproduct ((A$2:A$100=G2)*(D$2:D$100=-small(-D$2:D$100,20)))