How is the drop rate of TP from "random" bags calculated?

Anyone have any idea how the drop rate of all TP colours is calculated? I could really do with Green TP at the moment, most of the top of my roster have green moves and because they're 4sb-4ss it's around 190-230 to level up one. I get as much green TP as possible from the dailies each Saturday. I managed to get through a chunk of the road tours and got 26 of the 25 TP bags which I thought would give me a boost.

I opened those and got 75 green TP which is okay but not great, I also had 10 of the 10 TP bags and opened those but got no green this time! So it's not an equal drop rate, it's also not weighted towards the TP that your roster needs (or I'd have got more green from the 25s and at least some from the 10s!)

Is the drop rate weighted against the TP you most require!?

Sorry if this is common knowledge or there are other threads, I had a search but couldn't find anything related to TP drop rate.

Thanks!