Percentage of materials

Hmm, I would be a bit cautious about that. You use them for work, but perhaps also for private purposes?

If professional use really takes precedence, but there is still some private use... Then I would set the professional use at 75%. If professional use is really almost constant, but there is some private use in exceptional cases, you could perhaps go for a professional use % of 90.

This is not accounting or tax advice, of course! I don't know enough about the situation for that. But you often end up with a little private use. If you set the professional use percentage slightly below 100%, you immediately acknowledge this to the tax authorities.