Any way I can make it so each civ can only build X amount of settlers?

[Geoff741]

i'm trying to encourage expansion via conquest rather than AI cramming new cities in every tiny little gap, but I don't want to make settlers go obscelete half way through otherwise you could be completely screwed if you find you have no oil/alluminium and you can't gain any via conquest.

I've tried raising the cost rediculously but the AI buys them anyways rather than any buildings cause they're stupid.