Return the authors who wrote more than one book, with their book count and the average rating across those books. Group by author, filter the groups after aggregating, and order by count, highest first.
Expected: 2 rows. Georgi Gospodinov has 3 books averaging 4.43, and Yoko Tawada has 2 averaging 4.50. Count books, not rating rows: The Seven Moons of Maali Almeida has two ratings.