Third-party data on iOS 9 disputes Apple's adoption claims

Apple yesterday boasted that iOS 9, released less than a week earlier, had already cracked the 50% mark and had the "fastest iOS adoption ever."
But data from Mixpanel, which sells an analytics platform to mobile app developers for tracking usage and user engagement, did not support Apple's claim.
Although iOS 9 had accumulated a 39.7% share of all iOS editions as of 4 p.m. PT Monday -- and was several percentage points ahead of last year's iOS 8 at the same point in its post-release timeline -