Wizard lifespan/ Wizard population

[Hillman, Lee]

No: HPFGUIDX 13047

I've another thought that's been niggling me for a while. It concerns the
effect of the longer wizard lifespans on the population.
 
Anyone care to venture opinions as to this? 
 
It seems to me that if there are, as someone postulated, two dozen Weasleys
running around of various generations, and a lot of other branches of
wizarding families, this would add to the overall population and therefore
the economy. After all, if wizards live to an average age of 135, say (going
on the evidence that Dumbledore is 150 but looks 70's and McGonagall is 70
but JKR says that is "middle-aged" for a witch), it's more than possible to
have 4 or more generations of each family living at the same time.
 
We tend to base our population estimates on the fact that most people over
70 are not part of the working economy. Obviously that's not the case,
unless wizards are particularly prone to contracting strange diseases and
dying young.
 
I guess what I'm getting at in my inept way is that, taking two or more
"extra" generations into account, the wizard population could easily be
higher than we've been discussing it here.
 
Thoughts?
 
Gwendolyn Grace