Yeah, but that's the mobile market. That includes phones as well as tablets. Android has clearly made great inroads in the phone market: I think it actually has a market share of over 50% in phones (well, smartphones, anyhow). Unfortunately, the same cannot be said for tablets; for whatever reason, Apple still maintains a very strong position in the tablet market.

I'm too young to know for sure, but I bet Microsoft only ever had a monopoly in the desktop market and never in servers or the like.