Hmmm then perhaps something isn't right with the abundant setting. i see another thread out there with someone surprised how few stars spawned when he set it to "abundant" for that.
Still, 12 major and 4 minor races on a huge map (clusters) do make it seem busy so much so that if I had gotten say 9 black holes instead of just 5 I probably wouldn't have thought it was lacking, but yes, 12-13 was what I would've expected as well.