I have a bunch of copper ore mines with stations next to them, and the ore in them declines every now and then (It also happens when there aren't any trains in the stations). Is this normal? Also, in some stations the ore gets transferred from the mine to the stations rather slowly. The percentage transported in the mines is rather low, and because of this some trains leave the station only half full. Is there a way to improve this?
Srry if the answers can be found elsewhere, I'm currently playing with my brother and I didn't look very long

I am playing openttd 0.4.8, I'll attach the savegame
Thx in advance!