In the (A)D&D multiverse, when a deity gains believers, he/she/it also gains power. But how much might is gained as the number of followers increases?
As an example, when Elan's puppet deity has one follower — Elan himself — he can empower his priest to strike his adversary with a (very tiny) lightning stroke, doing probably no more harm than 1 HP, temporarily. Deities with millions of believers can, presumably, lay waste to whole landscapes. Is there an article or a table available where "power per believer" is listed?
AD&D 2.0 answers would be preferred, but all (A)D&D related answers are appreciated, as are also answers from other systems which could be converted.