Universe Sandbox 2 Discussion-: 9.97
Universe Sandbox 2 Help-------: 7.84
Astronomy & Science-----------: 10.63
Everything Else------------------: 26.13
It seems the the more open a board is, the more posts/topic there are. You can post almost anything in everything else, so it has more posts/topic. Astronomy and Science is fairly general too. Universe sandbox discussion is open to anything universe sandbox related and universe sandbox help has the least because there is not much to talk about, it is a very specific board.