Apple's new OS X Yosemite now powers about one in five Macs, an uptake rate that surpassed last year's Mavericks in first-month adoption speed, analytics company Net Applications said.
For October, Yosemite accounted for 19.4% of all instances of OS X tracked by Net Applications, which estimates operating system user share by tallying visits to the websites operated by its clients.
In comparison, OS X Mavericks, Apple's 2013 upgrade, ended October of that year with a Mac-only user share of 10.9%.
The difference was probably due to Yosemite's head start -- unlike Mavericks, Yosemite was seeded to about one million users in a first-in-14-years public beta program -- as well as its earlier release in the month. Yosemite appeared on Oct. 16, six calendar days before Mavericks, which debuted Oct. 22, 2013.
Accounts of Yosemite problems, especially reports of hampered or even crippled Wi-Fi, do not seem to have had a major impact on the OS's uptake.
Most of Yosemite's gains came at the expense of Mavericks, although 2012's Mountain Lion, 2011's Lion and 2009's Snow Leopard also lost small amounts of user share. Mavericks' drop of 11.6 percentage points -- the OS ended October with 51.9% -- was not only the largest since its launch but exceeded its first-month uptake of October 2013.
Lion and Mountain Lion now account for about 8% of all Macs each, while Snow Leopard, which has resisted replacement for a variety of reasons, ended October at just over 10%.
Apple has always been able to entice a larger percentage of its Mac users to upgrade, and upgrade faster, than Microsoft has with Windows. Apple has several advantages, including a much smaller user base, a history of less-expensive or even free upgrades, and most importantly, a predominantly-consumer pool of customers. Corporations typically upgrade the OSes of their work devices less often and at a slower rate than consumers.
The user share of Yosemite will be important to Apple, as it has hopes that the upgrade will spark sales not only of Macs, but also of iPhones and iPads because of "Continuity," the OS X-iOS feature set that allows task hand-off from an iOS device to a Mac, or vice versa.
Also important are the user shares of Lion, Snow Leopard and 2007's Leopard: Apple has dropped support for all three of the aged operating systems, and no longer provides security updates -- patches for vulnerabilities -- for the trio. When Apple patched OS X to protect against so-called POODLE attacks, for example, it omitted a fix for Lion.
The combined user share of Lion, Snow Leopard and Leopard last month was about 20%, or slightly more than Yosemite's.
OS X Yosemite can be downloaded free of charge from the Mac App Store, and supports iMacs as old as mid-2007, MacBook Pro notebooks from late 2007 on, and MacBook Air laptops from late 2008 going forward.