On the right side of the main site there's a box:
However when clicking the "stack exchange" link, I don't get to a statistics page about Worldbuilding, but to the list of sites, which makes no sense to me (it certainly doesn't contain any statistics about this site). I remember that in the past this linked to one of the User Reputation Leagues for the site, which makes more sense; in any case, it should link to some site-specific statistics page, as that is what is promised by the link.