Not intending to be braggadocios, but while going through my military records, I came across my nuke records.
NNPS, a 3.613 put me 14 out of 69
D1G prototype, a 3.178 put me 31 out or 96 (and I drank way to much, a miracle I made it, perhaps that week I was restricted to base had something to do with it.)
Now I do not know how this stacks up with grading today, but that was the spread in 67-68. It looks to me like at prototype, if a 3.178 put you in the top one third, there were a whole lot in the 2.5-3.0 region.
Was it a pump or a filter? I cannot really say, other then of the guys I went through the schools with, I can recall only four who dropped out. All for psychiatric reasons.