One thing Id emphasize on, is on the lower end of the chart (those with a few posts). Whilst these are the largest group by far on each local board, it may give a false sense of there being plenty of newcomer accounts that potentially will stay for the ride. The truth is, at least on the Spanish local board, that I barely actually see them at all, meaning that many of the likely post in the Altcoin board and/or spam something once in a lifetime, and/or got banned/nuked (the post count will still count their posts).
Another thing that I notice, at least in the Portuguese local tab, is that some users post more in the global tab than in the local one. So some who occasionally post locally can be very active in the global tabs.
Therefore, all these graphics are not considered all these details, which we have to account for when analyzing them in more detail.