How To Optimize Following Query For Execution Time

Hell All,
Following query takes 7 minutes to execute while using search criteria as shown below in blue text(ie. IN(2006,2007)
if criteria changes to =2006 as shown in 2),this takes 2minutes

But I want expected output as in query 1) in less time.
How to optimize following query for execution time?

1)select sum(PB.CONSN_QTY)Consumption,Count(*),PB.BillPro_Year
from tbtrans_prowaterbill PB
INNER JOIN MIDC_AREA MA
ON PB.Area_cd = MA.Area_cd INNER JOIN MIDC_Division MD ON MA.Div_CD = MD.Division_CD
INNER JOIN MIDC_Circle MC ON MD.Circle_CD = MC.Circle_CD
INNER JOIN TBMST_SubDiv TS ON MA.SubDiv_CD = TS.SubDiv_CD
INNER JOIN MIDC_Zone MZ ON MD.Zone_CD = MZ.Zone_CD
INNER JOIN tbmst_consumer TC ON PB.cons_no = TC.Cons_No
INNER JOIN TBMST_CONSTYPE TCT ON TCT.Cons_Type = TC.Cons_Type
where pb.billpro_year IN('2006','2007') and MTR_Size = 15 and TCT.Cons_Type = '1A2'
and MZ.Zone_Name = 'MUMBAI' and MC.Circle_NAME = 'MMR' and MD.Division_Name = 'Dombivli' and TS.SubDiv_DESC = 'THANE DIVISION STAFF'
group by PB.BillPro_Year





2)select sum(PB.CONSN_QTY)Consumption,Count(*),PB.BillPro_Year
from tbtrans_prowaterbill PB
INNER JOIN MIDC_AREA MA
ON PB.Area_cd = MA.Area_cd INNER JOIN MIDC_Division MD ON MA.Div_CD = MD.Division_CD
INNER JOIN MIDC_Circle MC ON MD.Circle_CD = MC.Circle_CD
INNER JOIN TBMST_SubDiv TS ON MA.SubDiv_CD = TS.SubDiv_CD
INNER JOIN MIDC_Zone MZ ON MD.Zone_CD = MZ.Zone_CD
INNER JOIN tbmst_consumer TC ON PB.cons_no = TC.Cons_No
INNER JOIN TBMST_CONSTYPE TCT ON TCT.Cons_Type = TC.Cons_Type
where pb.billpro_year = '2006' and MTR_Size = 15 and TCT.Cons_Type = '1A2'
and MZ.Zone_Name = 'MUMBAI' and MC.Circle_NAME = 'MMR' and MD.Division_Name = 'Dombivli' and TS.SubDiv_DESC = 'THANE DIVISION STAFF'
group by PB.BillPro_Year