NetMarketShare's (Net Applications) numbers are at odds to other web stat counters with more sites, page counting, no weighting by country, etc. E.g., W3 Schools or StatCounter:
Among other differences, NetMarketShare only looks at 40,000 websites, and they only count each visitor once a day. Meaning that if one visitor saw one page on a website, and another viewed 100 pages on that website, they count the same.
In other words, the counter used for this thread doesn't actually tell us web usage, only # of their sites visited.
Other counters like StatCounter track over 3 million websites, and count each page view, giving far more of a web usage view. (And even that would overcount browsers that tend to reload pages a lot.)
It's also likely that iOS would show up more often in North America due to the dominance of the iPad in that region.
There may not be a good stat source for this, unless we had access to those internal phone logs that used to tell the carriers such statistics.