Apple's not-quite-ready-for-release OS X Yosemite again boosted its user share last month, but the increase was only a third of the month before, recently released data showed.
In September, Yosemite powered 3.9% of all Macs, about six-tenths of a percentage point more than in August, analytics provider Net Applications said last week. That was 39 times the September 2013 user share of OS X Mavericks at the same point in its pre-launch timeline, and more than one third of Mavericks' share the following month, when it landed on the Mac App Store.
Yosemite's gains were offset by small declines in Mavericks, as well as in 2012's Mountain Lion and 2009's Snow Leopard. Mavericks' dip of two-tenths of a percentage point -- the OS averaged a 63.5% user share for September -- was the first since its launch in October 2013.
September's smaller increase for Yosemite -- in August, it jumped 2.1 points -- signaled that most who wanted to try the unfinished operating system had climbed aboard that bandwagon early on.
Apple released the Yosemite beta, the first open preview in 14 years, to the general public on July 24 and has updated it several times since then.
Apple has not named a ship date for Yosemite, but if it followed 2013's timetable, the most likely date would be Oct. 21. The company's scheduling of its third-quarter earnings call for the day before bolstered the Oct. 21 date. In both 2011 and 2012, Apple's chief financial officer announced the next-day availability of its newest OS X during the calls.
Last week, however, Re/code, citing unnamed sources, pegged the launch of OS X Yosemite for Oct. 16, when Apple is also to debut one or more new iPad tablets.
In 2013, Apple did flop the order of its earnings call and the launch of OS X, releasing Mavericks six days before the third-quarter call with Wall Street.
Net Applications measures OS user share by counting the OSes run by unique visitors to the websites of its 40,000-some clients.