Triple join with windows function

events.sql

SELECT
        city_name,
        extract(dow FROM events._ts) as dow,
        count(1) as trips,
        ROUND(count(1)/  SUM(count(1)) OVER () * 100, 2) as percentage
FROM events LEFT JOIN cities ON events.city_id = cities.city_id
            LEFT JOIN trips ON trips.client_id = events.rider_id
WHERE event_name = 'sign_up_success' AND
      city_name IN ('Qarth', 'Meereen') AND
      extract(year FROM events._ts) = 2016 AND
      extract(week from events._ts) = 1 AND
      trips.status = 'completed' AND
      extract(hour from trips.request_at - events._ts) <= 168
GROUP BY
      city_name,
      extract(dow FROM events._ts)
ORDER BY
      city_name,
      extract(dow FROM events._ts)
;