During world creation you can set the item’s spawn rate, and enemies spawn rate.
However I think the game would really benefit from being able to set specific spawn rates.
Some example groups:
Weapons, ammo, crafting (Components like gunpowder, paper, 2x4’s, etc) Food, Medical, CBM’s, fuel, etc.
Enemies: Robotic, Mutant, Zombie, Special Zombie, Animal (Natural), Animal (other), Survivors (NPC’s), plant, Insect, etc.
I would love to make cities overflowing with zombies with a tiny amount of specials sprinkled through, rather than either having the city flooded with specials, or none at all with a mod.