Queries :: How To Get Query To Display 0 If There Is No Data

I have a table where I record attendance. In the table they select the type of training in via a check box "Training, Drill or Other". I created a query to show how many times someone has attended the Drills in each quarter (counts the check box). I am wanting to be able to specify which year is displayed as atm it is showing all te quarters for years. The SQL is below.

From this I have a report where it displays the data and have conditional formatted it so that if they have not attended more than 4 times in one quarter the "cell" turns red - the only problem is is that some of the cells have no data in it. How can I get the query to display 0 if there is no data?

QUERY SQL:
TRANSFORM Sum(Abs([ATTENDANCE 2011].DRILL)) AS SumOfDRILL
SELECT [MEMBERS LIST].[NUMBER/NAME], Sum(Abs(Nz([ATTENDANCE 2011].DRILL,0))) AS [Total Of DRILL]
FROM [MEMBERS LIST] INNER JOIN [ATTENDANCE 2011] ON [MEMBERS LIST].ID = [ATTENDANCE 2011].ATTENDED.Value
GROUP BY [MEMBERS LIST].[NUMBER/NAME]
PIVOT "Qtr " & Format([DATE],"yyyy/q");