Adds a new number (giving it an appropriate weight) to the average.
Note that if too many numbers were added (more than ulong.max) then the
the internal counter will overflow (and as a result the average value
would be corrupt).
if that value represent in itself the average of other
numbers, then this param should define the number of elements
that this average stands for. A count = 0 has no effect on the
average and gets discarded.
Adds a new number (giving it an appropriate weight) to the average.
Note that if too many numbers were added (more than ulong.max) then the the internal counter will overflow (and as a result the average value would be corrupt).