What percentage of books written by Hirohiko make up the number of books published by Viz Media?
"Hirohiko Araki" is the author_name; 'Viz Media' is the publisher_name; percentage = Divide (Count(author_name = 'Hirohiko Araki'), Count(book_id)) * 100
SELECT CAST(SUM(CASE WHEN T1.author_name = 'Hirohiko Araki' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(*) FROM author AS T1 INNER JOIN book_author AS T2 ON T2.author_id = T1.author_id INNER JOIN book AS T3 ON T3.book_id = T2.book_id INNER JOIN publisher AS T4 ON T4.publisher_id = T3.publisher_id WHERE T4.publisher_name = 'VIZ Media'