Another interesting exercise that can be done for a given local board, which is quite revealing, is to break down the number of active posters on a given local board into groups, based on the number of posts that they've made.
That's exactly what I planned to do but then I scratched that idea due sheer laziness.

. Initial idea was to divide users into 3 groups: those who wrote 1 post, then group for 2-9 posts and 3rd for all that made 10+ posts. Does that make sense to you?
I might even try to do it today and if I can make it look good I'll update the overview with the new chart.