According to Apple's App Store Distribution dashboard for developers, iOS 8 was running on 63 percent of all iOS devices as of December 8, 82 days after its release in September. The operating system's adoption rate still lags behind iOS 6 and iOS 7's, but it's up a solid 16 percent since we took a look at it two months ago, and it now runs on a clear majority of active iDevices.

As we wrote previously, iOS 8's adoption is likely being limited by a bunch of factors: the fact that the update requires a substantial amount of free space to install, early evidence that it was a bit buggy and a bit slower on older hardware, and the fact that there's just more old iOS hardware floating around out there than there used to be.

Apple's numbers are calculated based on what devices access the App Store on a given day, but other independent data suggests that they are more-or-less correct. Data from Mixpanel shows that iOS 8 is running on around 63.94 percent of active iDevices as of this writing, while 33.42 percent run iOS 7, and 2.64 percent run an older version. Data from Fiksu's iOS 8 tracker shows adoption at a slightly lower 58.98 percent and that iOS 7 was running on 71.1 percent of active devices at this point in its lifecycle. iOS 6 and iOS 7 have roughly comparable adoption trajectories on Fiksu's chart, while iOS 8 tracks more closely with iOS 5 (the final version to require an iTunes connection for installation).

Though Fiksu's data is imperfect—its clients are largely based in Europe and the US, excluding data from most of the rest of the world—its iOS 8 tracker hosts lots of interesting numbers about both hardware and software adoption. For example, as of December 1, about 11.5 percent of people are using an iPhone 4 or older, suggesting that at least a tenth of all active iPhone users couldn't install iOS 8 even if they wanted to. The original iPad is being used by roughly 3.4 percent of iPad users, a smaller but still statistically significant number of devices that won't run iOS 8.

These numbers lend some credence to our theory that a larger pool of older devices is keeping a chunk of the userbase away from iOS 8. Further, people with Apple A5-based devices—the iPhone 4S, the iPad 2, and the iPad Mini, all of which have the most trouble running iOS 8—still make up a big chunk of the userbase. The iPhone 4S accounts for 16.8 percent of iPhones, and the iPad 2 and iPad Mini collectively make up 45.4 percent of iPad users. Assuming a statistically significant portion of these people have stayed away from the update because they're worried about performance, it could explain at least a few of iOS 7's remaining percentage points.

Finally, let's take a look at the iOS 8 adoption rate among a more tech-savvy audience. When we looked at data from late September into early October, around 60 percent of you had already hopped aboard the iOS 8 train. According to our analytics from the month of December so far, a little over 73 percent of you have moved on up to iOS 8, while a fifth of you hang on to iOS 7.

While iOS 8's growth and adoption rate lags behind that of its immediate predecessors, it still far outpaces update availability on other platforms. Google's developer dashboard, which like Apple's tracks OS usage by recording the devices accessing Android's app store, shows KitKat's adoption hanging out at about 34 percent over a year after its release. Lollipop, the most recent version of the OS, has so far been released primarily to Nexus devices, a handful of Motorola phones, and Nvidia's most recent Shield tablet. It's not yet visible on the chart.