These numbers are the most valid numbers we can find and match what we estimate based on other even less exact data (like the version check build into GitLab).

If you want to publish a research paper, "Yeah, I know this isn't really a valid measurement, but it's the best I can do" isn't going to cut it. This isn't a research paper, but honesty is honesty. If those are the best numbers you have, I would simply not say "X% of enteprises are using" -- because you don't actually know that. I'd say what you know instead, however you can describe it. Yep, it doesn't read as well marketting-wise, true.