"Wikipedia article traffic statistics" is/was the name of the certain website which was located at http://stats.grok.se
I made this category. So let me explain. "Wikipedia article traffic statistics" is/was the name of the certain website which was located at http://stats.grok.se
But now, "Wikipedia article traffic statistics" is offline, I suppose, for a long time.
And categorization in Commons doesn't work well as intended. It seems that most of the images categorized under this category are simply page view statistics, not about http://stats.grok.se