Aztec UA scaling?

[Bandobras Took]

I'm fighting in the industrial era and seem to be getting anywhere from +5 culture to +15 culture for killing enemy units.

Anybody have any clue what the formula is or why this is happening?

 

[KrikkitTwo]

1/2 strength of unit killed

 

[S.K. Ren]

Hee, 25 Culture for killing a Mech infantry... 75 for killing a GDR. Their ability works especially well on Immortal and Deity where the AI has an inexhaustible amount of troops to kill.