OOP: Prefects and their number

[Alon van Dam]

No: HPFGUIDX 62941

I'm sorry if I'm beating a dead horse here, but I haven't seen any of 
this in other posts, so here goes:

How many Prefects are there? Are there 8, 16, or even 24 prefects in 
Hogwarts School of Witchcraft and Wizardry?

In the fifth year, two students of each House are chosen. However, 
they don't resign in the sixth year... We know this from Percy, being 
Gryffindor Prefect in years 5 and 6 of his Hogwarts career (Books 1 
and 2.) But does this mean that new Prefects are chosen the next 
year, elevating the number of Prefects to 16? If this is not the 
case, it is highly unfair! This would mean that there are only 
Prefects chosen from every other year (or even once every three, see 
below). Highly unlikely, I believe. But this suddenly means that 
there are 4 Prefects per house... But how about the 7th year? I don't 
recall whether or not Penelope Clearwater is still a Prefect in PoA, 
but I do believe that is the case. It has also been implied that 
she's in Percy's year, which would mean that there are 6 Prefects per 
house, one of 5th, 6th, and 7th... It is possible that this isn't the 
case, and that there's only one Head Boy and one Head Girl of the 7th 
year and that the Prefects resign to be able to concentrate fully on 
their NEWTs.

Still: Where are the other 2 Gryffindor Prefects? Who are they? Don't 
Hermione and Ron need to have 'meetings' with them sometimes? Why 
haven't we heard of them at all?

On a side note: I was /so/ hoping for Ron to enter the Prefect's 
Bathroom and be completely speechless by the splendor thereof. But I 
think I'm alone in this ;)

Alon - Too Much Time On Hands