I'm the only one who can DELETE members and NO ONE is ever deleted unless they just create a membership to post their BUSINESS WEBSITE - and most of those are SPAMMED by software, not created by a real person - we've had a bunch of adult related sites over the last year that I've tossed.
But if you SORT members by NUMBER of posts, you will see that 53% of all members NEVER post a single post - that is just how it is in forums. So going by your math, we should have about 180 members - and it just isn't so.
So, you weren't deleted because of inactivity - nor any other reason that I know of, and I'm the guy with my finger on the button.
Beemaster isn't an UNMODERATED forum, we have mods and an Admin guy (me) who are here very often - so whether you forgot a password, or if your username was spelled different and you couldn't log in or as Jerrymac said got lost when we had a software crash and had to reboot from an older saved file, I don't know. But neither do the software or me boot anyone for inactivity, it just doesn't happen like that.
PS... Great chart Leominster, neat seeing the membership growth relative to month vs overall - thanks for that :)