I agree with you that the Moodle usage stats seem inflated/unfiltered, which makes them unusable (IMO). Interestingly enough, my institution has a bona fide Moodle enterprise installation (albeit with about 20% or less of our online classes; Blackboard is our primary LMS) yet we aren’t in your list. Makes me wonder if it’s really possible to identify the “real” installations from the many projects and one-off downloads.

Lane at Central Piedmont Community College
Charlotte, NC