=SIERREUR(RECHERCHEV(B2;$B$2:$C$24;2;0);0)
=SI(OU(B2="";NB.SI($B$1:B2;B2)>1);"";SOMMEPROD(($B$2:$B$24=$B2)*(($C$2:$C$24/NB.SI($B$2:$B$24;B2))-$I$2:$I$24)))
=DECALER(Feuil1!$B$2;;;NBVAL(Feuil1!$B:$B)-1)
=SOMMEPROD(1/NB.SI(BC;BC)*DECALER(BC;;1))
=DECALER(Feuil1!$B$2;;;NBVAL(Feuil1!$B:$B)-1)
=SOMMEPROD(1/NB.SI(BC;BC)*DECALER(BC;;1))
=DECALER(Feuil1!$B$2;;;NBVAL(Feuil1!$B:$B)-1)