It's funny you say this, because these numbers are debatable. The wc3stats OS site claims the Linux pie slice is around 5%, whereas Microsoft (Years ago... At that) conjectured Linux usage at roughly 8%.
Statistics are difficult to trust, and are often very misleading. While I might be a Linux fan, it doesn't make me lose my objectivity. WinP7 is such an example. I don't trust current statistics (e.g. The recent drop in market share for MS). Likely they're floating a little above that number, but the statistics don't cover the entire scale well.
Such are the woes of statisticians- their task I do not envy
