Four years ago at the Ubuntu Developer Summit in Budapest, Mark Shuttleworth - founder of the Linux distribution: Ubuntu - stated "Our goal, our mission, is 200 million users of Ubuntu within four years." It's now the end of the time frame that Shuttleworth set and it appears that Ubuntu has not amassed its predicted 200 million users.
As Ubuntu is rarely shipped on marketed products, it has no sales figures. This makes it difficult for Canonical - Ubuntu's parent company - to give precise figures and therefore doesn't release official stats. Despite this, unofficial estimates place the total number of desktop and server installs in the tens of millions, but not surpassing 100 million.
Since Shuttleworth announced his ambitious target, we've seen a huge push in the enterprise sector with their cloud offerings. On the consumer front we now have Ubuntu Touch which has begun shipping on devices this year. Some products Shuttleworth hoped to bring to market, such as Ubuntu TV and Ubuntu for cars has, so far, not happened.
Although the goal of 200 million users hasn't been met, we could still see Canonical gain significant numbers of users in coming years as they shift their focus to mobile, the Internet of Things (smart devices), and the enterprise.