No sooner had Apple senior vice president of worldwide product marketing Phil Schiller taken the keynote stage at Apple’s Worldwide Developer Conference (WWDC) before he announced that Apple has tripled its active user base in the past two years. The secret, of course, is the success of the iPhone.

Schiller produced a chart showing the number of actual active OS X users from 2002 - 2007. By the end of 2007 Apple counted about 25 million active OS X users.

In the past two years, there’s been a “huge spike” of new OS X users, according to Schiller, and Apple has seen the user base grow from 25 million to near 75 million users today, in 2009. That's thanks to extraordinary success of the iPhone and iPod touch, which both run a version of OS X.

“No wonder everybody’s trying to race behind us and follow in our footsteps,” quipped Schiller.

Editor's note: Due to a reporting error, it was originally indicated the number of Mac OS X users had increased from 25 to 75 million. That has been corrected.