I think he means "active member numbers", Rick. Every member of the club is deemed active, or he wouldn't be a member. If he doesn't renew when his membership expires, he's no longer a member but I believe his number is kept available in case he rejoins within a certain period of time.

In any case, I don't think any member number is reused for a different collecter so the highest humber assigned is representative of the number of collectors who have ever been members, except for spouses and any who rejoin after the grace period ends.