Supply Stock Levels

[Leeds]

Have seen cities with stock levels at 500/400 levels, I presume this means a major depot or source level.

How much does a source, city, state, etc get depleted per turn?

Not to sound dumb, but how many provinces/regions away from a major source will I see detrimental supply effects?

Will these effects be greater - or at lesser distance - if the suplly stock level of the source is say 10/10?

[Gray_Lensman]

deleted

[Rafiki]

Here's a link to the wiki article dealing with supply distribution: http://www.ageod.net/aacwwiki/Supply#Supply_distribution