Oracle SQL script needs finetuning in TOAD

Hi All,

I need to somehow simplify/finetune this long query, as it takes about 1/2 hour to run, if not more! Any suggestions?

Regards,
Bernard

SELECT ROUND(AVG(GR.GR),1) Grading,
	   ROUND(AVG(RR.RR),1) Resheeting,
   	   ROUND(AVG(PR.PR),1) Pave_Repairs,
	   ROUND(AVG(SW.SW),1) Shoulder_Work,
	   ROUND(AVG(RF.RF),1) Road_Furn,
	   ROUND(AVG(FW.FW),1) Foot_Work,
	   ROUND(AVG(KCW.KCW),1) Kerb_Channel,
	   ROUND(AVG(SGPW.SGPW),1) Sign_Post,
	   ROUND(AVG(DW.DW),1) Drain_Work,
	   ROUND(AVG(RCU.RCU),1) Cust_Req
FROM


	(

	SELECT DECODE(GRADING_ROADS, 0, 2.5, GRADING_ROADS) AS GR
	FROM V_NM_CUSU
	WHERE IIT_DATE_CREATED BETWEEN TO_DATE('01/01/2006','DD/MM/YYYY') AND
TO_DATE('31/12/2006','DD/MM/YYYY')
	AND GRADING_ROADS <> 5
	) GR,


	(

	SELECT DECODE(RESHEET_ROADS, 0, 2.5, 5, 0, RESHEET_ROADS) AS RR
	FROM V_NM_CUSU
	WHERE IIT_DATE_CREATED BETWEEN TO_DATE('01/01/2006','DD/MM/YYYY') AND
TO_DATE('31/12/2006','DD/MM/YYYY')
	AND RESHEET_ROADS <> 5
	) RR,


	(

	SELECT DECODE(PAVEMENT_REPAIRS, 0, 2.5, 5, 0, PAVEMENT_REPAIRS) AS PR
	FROM V_NM_CUSU
	WHERE IIT_DATE_CREATED BETWEEN TO_DATE('01/01/2006','DD/MM/YYYY') AND
TO_DATE('31/12/2006','DD/MM/YYYY')
	AND PAVEMENT_REPAIRS <> 5
	) PR,


	(

	SELECT DECODE(SHOULDER_WORK, 0, 2.5, 5, 0, SHOULDER_WORK) AS SW
	FROM V_NM_CUSU
	WHERE IIT_DATE_CREATED BETWEEN TO_DATE('01/01/2006','DD/MM/YYYY') AND
TO_DATE('31/12/2006','DD/MM/YYYY')
	AND SHOULDER_WORK <> 5
	) SW,


	(

	SELECT DECODE(ROAD_FURNITURE, 0, 2.5, 5, 0, ROAD_FURNITURE) AS RF
	FROM V_NM_CUSU
	WHERE IIT_DATE_CREATED BETWEEN TO_DATE('01/01/2006','DD/MM/YYYY') AND
TO_DATE('31/12/2006','DD/MM/YYYY')
	AND ROAD_FURNITURE <> 5
	) RF,


	(

	SELECT DECODE(FOOTPATH_WORK, 0, 2.5, 5, 0, FOOTPATH_WORK) AS FW
	FROM V_NM_CUSU
	WHERE IIT_DATE_CREATED BETWEEN TO_DATE('01/01/2006','DD/MM/YYYY') AND
TO_DATE('31/12/2006','DD/MM/YYYY')
	AND FOOTPATH_WORK <> 5
	) FW,


	(

	SELECT DECODE(KERB_CHANNEL_WORK, 0, 2.5, 5, 0, KERB_CHANNEL_WORK) AS
KCW
	FROM V_NM_CUSU
	WHERE IIT_DATE_CREATED BETWEEN TO_DATE('01/01/2006','DD/MM/YYYY') AND
TO_DATE('31/12/2006','DD/MM/YYYY')
	AND KERB_CHANNEL_WORK <> 5
	) KCW,


	(

	SELECT DECODE(SIGN_GUIDE_POST_WORK, 0, 2.5, 5, 0,
SIGN_GUIDE_POST_WORK) AS SGPW
	FROM V_NM_CUSU
	WHERE IIT_DATE_CREATED BETWEEN TO_DATE('01/01/2006','DD/MM/YYYY') AND
TO_DATE('31/12/2006','DD/MM/YYYY')
	AND SIGN_GUIDE_POST_WORK <> 5
	) SGPW,


	(

	SELECT DECODE(DRAIN_WORK, 0, 2.5, 5, 0, DRAIN_WORK) AS DW
	FROM V_NM_CUSU
	WHERE IIT_DATE_CREATED BETWEEN TO_DATE('01/01/2006','DD/MM/YYYY') AND
TO_DATE('31/12/2006','DD/MM/YYYY')
	AND DRAIN_WORK <> 5
	) DW,


	(

	SELECT DECODE(RCU, 0, 2.5, 5, 0, RCU) AS RCU
	FROM V_NM_CUSU
	WHERE IIT_DATE_CREATED BETWEEN TO_DATE('01/01/2006','DD/MM/YYYY') AND
TO_DATE('31/12/2006','DD/MM/YYYY')
	AND RCU <> 5
	) RCU