Depends on your perspective, I suppose. But I was just talking to a web- and app-based service company that started on the Microsoft stack circa 2001. They're migrating away from it partly because of tech issues, but mainly because it's much harder to hire people.

If you look at yesterday's "who's hiring" post, it's way, way less than a third of positions that are using Windows server technologies.

How many of those Windows servers are only running Exchange and Active Directory and nothing else? If I had to guess, I'd say 70% or more but maybe someone else has better estimates.

70%+ is probably accurate if you include the whole microsoft enterprise ecosystem (sharepoint etc in addition to what you mentioned)

windows is definitely a minority in web hosting

The windows devs I know just use whatever comes from Microsoft and are not interested in anything else. They believe Microsoft has the best tech :)