(
	CAST( SUM( r.price ) AS FLOAT ) /
	ISNULL(
		NULLIF(
			(
				SELECT
					SUM( r2.price )
				FROM
					reward r2
				INNER JOIN
					[order] o2
				ON
					r2.order_id = o2.id
				WHERE
					o2.user_id = u.id
			),
			0
		),
		1
	) *
	100
) AS percentage_used