well you dont get a box every single time you post, and you seem to get a green box fewer times than the red one, for me its about 50% of the red boxes
I haven't spent any of the green yet and I have 167 of them. Getting to at least 230 was my original goal, but now I'll settle for whatever I can manage to get I think XP
I also have two of the raindeer horns, been trying to trade them for something else in the exchange but no luck so far.