I recon it is the most used calibers Worldwide you're interested in?

I think John is pretty cloe to "the right" answer, with a little adjustment..:

9.3x74R - since A Lot of rifles has been made in this chambering for a long time in europe. The 9,3mm (x74R in break open rifles) has been the standard for driven boar hunts, and for moose and red-deer, among "well situated" hunters for decades.
.470 NE
.450/.400 3" (I still think there are more .470 around than .400s, due to more beeing made in recent years)
.375 H&H Mag belted..
.450 3 1/4"
.450 No.2
.375 Flanged Magnum