Default sum in ccc2 barchart

Hi all,
i have a simple question.
Suppose I have a query which returns more numeric values for the same row (suppose to have days on row and numeric values on columns. E.g. i have 100 for day 1 and another value 200 for the same day 1).

So, the barchart get the SUM of these values, plotting 300.
Instead, i want it made the Average, obtaining the value (100+200)/2=150. Is this possible?

Thanks.

Marco