The Society pieces would be different than Limited Editions or Open Editions, (which, I suspect, would also be very limited in the later releases, especially where a bunch of them were discontinued). Because it was a membership thing, HL would have had an idea as to how many to make just by using the previous year's numbers. The trend from year to year as far as how many members the Society lost or gained would have been carried over with each new year when production was ordered.