[gocard14]

You raise a fair point, but your analysis neglects the fact that contributions will naturally be weight much more heavily towards upperclassmen, and that many people will be significant contributors but only for 1-2 years.  If we accept your hypothesis that about 45 people will be meaningful contributors, in the most extreme setting that could mean that every junior and senior is a meaningful contributor with a few undercalssman and fifth year contributors. 

[gocard14]

You raise a fair point, but your analysis neglects the fact that contributions will naturally be weight much more heavily towards upperclassmen, and that many people will be significant contributors but only for 1-2 years.  If we accept your hypothesis that about 45 people will be meaningful contributors, in the most extreme setting that could mean that every junior and senior is a meaningful contributor with a few undercalssman and fifth year contributors.