short question on upkeep

[onomastikon]

Just wondering: I seem to be giving way too much of my income out for "upkeep", and was wondering how I can lower this a bit. Maybe I dont summon enough. In any case, have been playing Ulm, because I like the idea of fewer, more sturdy units -- but are these heavier on the "upkeep"? How is upkeep actually calculated? From Cherry's "Newbie" thread I dont totally understand. Thank you.