It's generally in the 70-90% range. Right now, it's much easier to argue that Android has a global monopoly.
> There is no need to have a "clear" monopoly like Windows in 1990's to abuse your power and presence in the market.
Well it depends what you mean by "abuse". I mean, even small companies can "abuse" their customers by not building the interoperability their customers want. But we generally prioritize individual freedom, that private businesses ought to have free choice in what they work with or don't. That's important.
That only becomes a problem when consumers aren't able to switch to a competitor. I.e. when there is a monopoly provider. I.e. which controls 70-90%+ of the market.