Yes, although it's not evenly distributed. Much of this rise is due to India doing some heavy lifting - they're on like 16%, and they're not exactly a small population.
Indeed it is. But this is also calculated based on monthly page views, so it only really covers devices that are used in that month.
There's a non-trivial amount of Windows users that have a dusty laptop that they only pull out when they need to write a document or fill in a form that they got emailed, and will otherwise do all their computing on their phone.
My guess would be that Mac and Linux have fewer of these types of users? But who knows. I have a couple of Linux devices that I almost never use 🤷♀️
There's some kind of network effect associated to it, so the greater the numbers, the more likely to grow even more, and faster. For example, when linux was used only by a very few people in IT, most people were unlikely to even give it a try, but now that every class or working group are likely to have one or two linux users, more people will be likely to try it, and so on.