Goodreads Librarians Group discussion

Trying to understand how the Statistics readers have listed against them are calculated.
Top readers have over 500 books as read this week. I know people can read fast, but 70 books a day, seems a tad high
Top Reviewers are reviewing 70 a week, or 10 a day. Again reading and reviewing that many seems a lot

Are the statistics calculated on literally one for one, or is some algorithm giving credits for the number of pages or words submitted ?

Only the staff will know the list are exactly made. But it seems it is about books or reviews added that week, not necessarily read that week. So someone adding books they have read in the past might get them high on the list.