I think Apple is more on the US market. If you see it worldwide, Linux is more important. In the EU, China, Russia the big migrations are always from Windows to Linux - never heard that a eg. a government or schools migrate desktops from Windows to Apple, on the other hand the administrations of many cities in Europe for example Munich 14000 desktops, Vienna 12000 desktops and so on migrate to Linux.
Apple is Killing Linux on the Desktop