About three years ago, WordPress introduced pie charts and a stats API to the plugin repository. These stats gave plugin authors a chance to see which versions of their plugin were activated while also giving a glimpse into how many actual users the plugin had. The API provided a method to getting access to the data. Unfortunately, the API along with the Pie charts have been temporarily removed.
According to ticket #107 which states that the pie charts were reporting erroneous data, Otto responded “until we can sort out the stats gathering system, this was no better than random numbers“. I sent an email to the WordPress.org team to see if any progress had been made on this problem. Their response is that they have not looked into it yet. It will be worked on at some point, but it’s not high on the priority list at the moment.