SELECT tt.request_at, tt.driver_id, YEARWEEK(tt.request_at) as yearweek, COUNT(tt.driver_id) FROM trips tt
INNER JOIN cities cc ON tt.city_id = cc.id
WHERE tt.request_at >= "2014-03-01" AND tt.request_at <= "2014-03-31"
AND cc.name = 'new_york' AND tt.status = 'completed'
GROUP BY tt.driver_id, yearweek;