I have just realised that below the section "Forum History (using forum time offset)", inside the Statistics Center, there is only data until December 2017.
What is the reason for this lapse?
I would like to know that too. Does anyone know why theymos disabled "Monthly Summary" statistics from Forum History?
Probably because it caused too much strain on the servers' resources but don't quote me on that, I just vaguely remember some reply somewhere from theymos that paraphrases the former.
Edit:
reference which somewhat implies it;
I might've figured it out. A bunch of things are currently disabled; I'll work on safely enabling them in the coming days.
BTW: You can also use similarweb & Alexa to get a more general idea of the real amount of visitors & retention time etc.