SELECT Queue, Agent, AVG(March) AS AVG_March, AVG(April) AS AVG_April, AVG(March) AS AVG_May
  FROM ( 
	   SELECT  q.[description] AS Queue
		 , a.firstName + ' ' + a.lastname AS Agent
		 , (select s.score where s.period='03/01/2004') AS March
		 , (select s.score where s.period='04/01/2004') AS April
		 , (select s.score where s.period='05/01/2004') AS May
	      FROM agent a 
	 LEFT JOIN service_level_report s
		ON a.id = s.id 
	      JOIN queue q
		ON q.queueid = s.queueid 
	     WHERE q.active = 'Y' 
	       AND a.active = 'Y' 
	       AND s.period BETWEEN '03/01/2004' AND '05/01/2004' 
	       AND s.callscompleted <> 0
) AS XXX
GROUP BY Queue, Agent