Then, in 2022 when the average registration per day increased by more than 400% making it 301.43 registration per day, the number of online per day decreased to 127.26
It looks like the Statistic Center is based on
this mod. The description states that the Admin can tweak the parameter settings for the period of time, setting it accordingly to fit one of these options:
This mod allows you to select periods for which to display the forum statistics.
You can choose between first/last x days/weeks/months/years or custom start and end dates OR their combination.
Not sure how the parameters are set here, but I presume that the period is set globally to the Statistics Center to keep a consistency in the displayed data (as opposed to set per counter).
Having said that (as a context), it seems clearly inconsistent: If we take the average posts per day in 2022, and contrast it to the average number of user online per day, we get a ratio of over 43 posts per day per active user. The ratio is just over 3 in the 2012 snapshot.
Note: there are probably many bot type registrations nowadays with 0 posts, than back in 2012, so the average number of registrations per day may not represent accounts with real intent to participate in the forum.