Materials from cargo planes.

Good evening,
I have a question abouth the materials from cargo planes for making XL planes.
I have at this moment 2100 + cargoplanes. The most up to 4 hrs, because they give you metal you needed for every XL plane. We need more metal as something else, okay thats the game. But we need also a lot of bolts, and that is also difficult because there are only 11 different planes who gives you that. And there are two planes you have to buy in the shop for cash and one you get for free. (1 time only 1)
If i send all my cargo planes , i got about the next materials:

Bolts----------139
Metal----------331
Synthetics----554 !!!
Electronics----485 !!!
Fabric---------255 !!!
Glass----------111



I have counted the materials we needed for making all the XL planes (the usual)
I have only made the next materials.

Bolts--------730
Synthetic---599
Electronic---569
Fabric-------452.

So, you can see what we get and what we needed. My problem is,(and i think many more players) why we get a lot of Synthetics, Electronics and Fabric ? What we do with those ? We got more and more, and we not need so much.
Is it not possible to change something, so that we got more Bolts, metal and glass instead of the others. I know you guys flying also like us , so you understand my question.

Thanks and kind regards.

olandiano

P.S.
Also another possibility is that the players who got your cargo planes, get also the materials for building the X-planes. They got the boxes but not the parts for building.
Or put some boxes with those materials in the shop, for coins or cash. Skyrama receive. more money also