The Winter of Lost Content was in 2001-2002. I know because I joined in late 2001 and all my original posts were vanished. That’s also why I’m listed as having joined March 11, 2002. My 20th anniversary is coming up much sooner than next March.
In this post from November 2019, TubaDiva says almost 22 million posts at that time, so it looks like your count is pretty good.
Long time ago? Like from the Great Chicago Fire?
Take Beckdawrek’s and divide by 2