The newest version of the Mac operating system is off to a blistering start, according to data released Wednesday by the Chitika ad network. The key findings:
- Within three days, OS X 10.10 represented 0.15% of U.S. and Canadian web traffic. It took OS X 10.9 Mavericks a month to reach 0.05%.
- Within a month, Yosemite developers were generating 0.2% of North American Mac OS X traffic — nearly four times the share Mavericks developers generated last year in the same time frame.
- Meanwhile, Mavericks’ share has grown to 45.7%, an increase of nearly 6% since Chitika’s March survey.
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If history is any guide, it’s going to take the Mac-using public considerably longer to make the switch. According to the Chitika pie chart below, the second most popular version of the Mac operation system, after Mavericks, is five-year-old OS X Snow Leopard.
As a software ecosystem, OS X looks more like Google’s (GOOG) Android that Apple’s (AAPL) iOS.
Follow Philip Elmer-DeWitt on Twitter at @philiped. Read his Apple coverage at fortune.com/ped or subscribe via his RSS feed.