Google revealed this week that Android versions 5.0 and 5.1, dubbed Lollipop, are now running on 36.1% of all Android-based devices, just topping Android 4.4 KitKat’s 34.3% market share. This is the first time that Lollipop has been named the most popular Android version, and it took the platform 16 months since its launch to reach the pinnacle.

Android “fragmentation” is an issue that Google (GOOG) has been trying to counter over the last several years, but the update cycle is fraught with potential delays. Google has been pushing vendors to update their devices more quickly, but after a new version of Android is launched, it first needs to go to smartphone makers, who then decide whether to upgrade or not. If they do, they need to push the updates through carrier networks, and those carriers can often take a long time to push the software to end-user devices.

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That a 16-month-old operating system is now the most popular Android version could also prove concerning to consumers. While Lollipop has been widely viewed as a fine platform, Google’s 2015 launch, Marshmallow, comes with some enhancements to design and security. However, it’s only running on a handful of devices and updates are slowly making their way to others. As of this writing, Marshmallow has just 2.3% market share.

For developers, knowing what version of an operating system the vast majority of users are running is critical, since it tells developers how widely it should spread resources to ensure an app works on all versions of a platform. The fewer the versions, the fewer the operating systems developers need to evaluate. That can often create a better app with fewer glitches and better features.

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Apple (AAPL) has made that point on several occasions over the last few years at its Worldwide Developers Conference. The company continually says that it does a better job than Google and its Android partners at getting customers to the latest version of its software. Indeed, as of Feb. 22, 77% of all iOS users were running last year’s iOS 9. Just 17% were running 2014’s iOS 8.

That said, Apple has an easier path to upgrading users. It’s the only company peddling iOS, and it installs its latest operating system in every new version of its iPhones and iPads. Apple also pushes out iOS updates to users directly, taking out many of the speed bumps Google must contend with.

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Now that Lollipop is tops in the Android world, it will likely remain so for the foreseeable future. Meanwhile, Google is rumored to be working on a new Android operating system for this year, which will add yet another to the mix.

One other interesting tidbit from Google’s data: Millions of Android users around the world still run Android’s Gingerbread. That operating system first launched in 2011.