Wall Street Journal:

Four days after AppleAAPL -1.12% released an update to its mobile operating system, more than a quarter of app traffic is coming from iPhones and iPads running the latest software, according to data from analytics firm Mixpanel.

Apple released iOS 7.1—the first major update to its mobile software since its debut in September—on Monday. The update addressed some of the major complaints users had with the software including the tendency to crash and reboot often and the unreliability of its fingerprint sensor for its iPhone 5S. As of Friday, Mixpanel said 26.4% of app traffic is coming over devices running iOS 7.1, slightly less than the 31.5% usage rate for its previous version, iOS 7.0.6.

While this doesn’t mean that 26.4% of iOS devices have the update installed—people who use more apps more of the time may be earlier to adopt upgrades, after all—but it shows momentum, especially compared to the competition. About 6% of app traffic on Google’s Android operating system stems from “KitKat,” the latest version of the software released in October, Mixpanel said.

Great numbers.