Some quick testing numbers:
Level | Min% | Avg% | Max% |
1 | 40 | 45 | 50 |
2 | 50 | 60 | 65 |
3 | 55 | 70 | 75 |
4 | 60 | 75 | 80 |
[My observation, moving a couple of large guild camps at Salvage Level 4, has been that the variation is not very great when there are a large number of items involved. For example, when I recently salvaged 4 Clinker Vats, the number of bricks was always within just a few bricks of 4000. If there are just one or two of an item in a building, such as clay domes in a rabbit hutch or brass plates in a barrel vise, you may or may not get any back at all. So it appears to me, at least, to be a base percentage, minus a random number (maybe 0 to 3?) of the item. This is something that needs further testing by more individuals. -- Solalique]