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/* relative share of each film category in - total rental revenue - total number of rentals */ SELECT c.name AS category, SUM(p.amount) / SUM(SUM(p.amount)) OVER () AS relative_rental_amount, COUNT(*) / SUM(COUNT(*)) OVER () AS relative_rentals_count FROM rental AS r JOIN payment AS p ON p.rental_id = r.rental_id -- each payment belongs to one rental JOIN inventory AS i ON i.inventory_id = r.inventory_id JOIN film_category AS fc ON fc.film_id = i.film_id JOIN category AS c ON c.category_id = fc.category_id GROUP BY c.name ORDER BY relative_rental_amount DESC;