Template:CatTrack
Tags categories to be logged by the CatTrack tool, which logs the size of categories over time. For example, see the CatTrack page for the population of Category:All unreferenced BLPs.
Many of the transclusions of this template come from {{Backlog}}, which transcludes this template.
Usage
{{CatTrack}}
This code will cause the category page it appears on to be tracked in the CatTrack tool. You may have to wait a week or so for data to start appearing.
A full list of tracked categories is available.