How can record the total amount of prefabs that are spawned during runtime?

Hello folks,

I want to create a script where prefabs of one kind will stop after 30 times of being spawned, After this, another prefabs of a different kind will follow up.

To create this script I need a part of code that will count my spawned prefabs but I couldn't find any information on how to do this?

From a script I found this:

 var PrefabCount : int; // Number of Prefabs in the game at a time

but it says at a time, as my game is also deleting the prefabs out of sight it will not work. I need a script that will also take the deleted prefabs into account.

Any tips and suggestions are very welcome :)

Thanks anyway.