Also based in NL, "Amsterdam" area (Utrecht). As people have mentioned elsewhere, it depends. My current long-term (6+ months) contract is at €95/hr, working as part of a great team of developers on an Elixir backend, and being able to learn Elixir (which I didn't know beforehand) on the job. I have also done smaller projects (2 months), a bit more specialized, on the side for €125/hr.
By the way, I am not totally convinced about weekly vs hourly billing. In my case, hourly billing has worked well. I just make sure I bill for _everything_ I do for the client, also the time I spend learning stuff, and communicate clearly about it. People hire me because I can figure out stuff quickly, not because I know all there is to know about programming (though I do think I have a strong background).