I'm not surprised with 70% for Chrome. Every Android phone comes with a Chrome browser. Too bad Mozilla mobile strategy didn't work. times and times again I said to whoever was in charge with the project :"Target hipsters, and hackers, not emergent economies and low hand devices, make it the phone for those who can afford a third one with good specs and are trend setters, or engineers, they'll develop cool shit for Firefox OS!", but no, they went with cheap and low end, ignoring the fact that a pure HTML/JS phone will perform worst than a phone that runs C apps and Java... People in third world countries don't give a f. about HTML/JS, they want their phone to run skype and whatsapp ...
For what it's worth, agreeing on a strategy with phone vendors and OEMs is much harder than it looks. Decision-makers in this domain have very different processes and goals than in software development. Plus it's very much a shark-eats-shark world.
So I don't actually know who took the decisions, but I wouldn't be so sure that it's Mozilla.
I wonder why countries aren't pursuing Apple and Google about the monopoly of their browsers on their platforms as they did with Microsoft over IE. Apple in particular is obviously extremely anti competitive, at least you can install a gecko based Firefox on Android, on iOS it's webkit based.