Microsoft is selling 20 million devices/year with about 100% YOY growth if memory serves.

Apple is at 6 million/year, no YOY numbers yet.

Symbian is selling about 140 million devices/year.

The numbers are not to be directly compared if you care about "smart" part of the "smartphone" - most Symbian users are not using any smart features, whereas many of Microsoft users do and so does practically every single Apple user.