---

SELECT
    ROUND(
        COUNT(DISTINCT active_users.user_id) * 100.0 / COUNT(DISTINCT Users.id),
        2
    ) AS percent
FROM Users
LEFT JOIN (
    SELECT user_id FROM Reservations
    UNION
    SELECT owner_id AS user_id FROM Rooms JOIN Reservations ON Rooms.id = Reservations.room_id
) AS active_users ON Users.id = active_users.user_id;