=MOYENNE(SI(ESTNUM(B3:B111);DATEDIF(B3:B111;A3:A111;"y")+
(DATEDIF(B3:B111;A3:A111;"ym")/12)))
=ENT(MOYENNE(SI(ESTNUM(B3:B111);DATEDIF(B3:B111;
A3:A111;"y")+(DATEDIF(B3:B111;A3:A111;"ym")/12))))&" ans et "&
ENT(MOD(MOYENNE(SI(ESTNUM(B3:B111);DATEDIF(B3:B111;
A3:A111;"y")+(DATEDIF(B3:B111;A3:A111;"ym")/12)));1)*12)&
" mois"