going from 8 artist to 9.5 artist

I have cubase 8 artist 64 bit (Windows 10).
Was going from 8 to 8.5 a paying or a free option?
If the later, why is it more expensive to go from 8 to 9.5 than from 8.5 to 9.5?

Cubase 8.5 was a paid upgrade, otherwise it wouldn’t show up as an upgrade option.

ah, ok, that makes sense!