Ballmer announced Friday that he would retire from Microsoft in the next 12 months. Here’s a by-the-numbers look at his decade-plus run as the software giant’s leader.

Robert Galbraith / Reuters

After running Microsoft for more than a decade, CEO Steve Ballmer said Friday he would retire in the next 12 months once his successor is found.

The announcement essentially brings to an end an extended period of investor frustration with Microsoft. While Ballmer methodically and slowly grew the company into a behemoth, shareholders have been looking at the quick and massive growth of major competitors Google and Apple during the same period and are left to wonder what might have been.

Throughout Ballmer's tenure, Microsoft stock has basically flatlined — that is, until today's retirement announcement, which sent shares up nearly 8% in trading.

The two biggest questions now are who will take over for Ballmer and can that person keep it from going through another "what might have been" period. With that in mind, here are a few highlights and lowlights from Ballmer's tenure, by the numbers.

**Editor's note: Microsoft doesn't break out Windows sales figures, only licenses, so its most important product is note quantified here.**