Question: What is the percentage of books that cost greater than $10 and were ordered by customer Ruthanne Vatini?
SQL: SELECT CAST(SUM(CASE WHEN T1.price > 10 THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(*) FROM order_line AS T1 INNER JOIN cust_order AS T2 ON T2.order_id = T1.order_id INNER JOIN customer AS T3 ON T3.customer_id = T2.customer_id WHERE T3.first_name = 'Ruthanne' AND T3.last_name = 'Vatini'