http://3cbzkrvakrpetjjppdwzbzqrlkmzatjs7jbyazap5gwutj32gcltjpqd.onion
You'd intuitively
think that 50/50 would be a good idea, but if you have e.g. 40 elements,
you'd much rather split them 32/8… if you can find perfect hashes for
both subgroups (5-bit and 3-bit, respectively). If not, a 20–20 split
is most likely better, since you very easily can find magics that put
20 elements into 32 buckets without collisions.