Percentage calculation in crm 2011 charts

Hi all,

I am trying to get percentage calculation in default CRM 2011 charts. CRM provides aggregates functions like count,sum,average,min,max methods. But it does not have Percentage calculation function.

Here is the fetch XML generated by CRM 2011 chart to get sum of revenue field of account

<fetchcollection>

        <fetch mapping="logical" aggregate="true">

          <entity name="account">

            <attribute groupby="true" alias="groupby_column" dategrouping="month" name="createdon" />

            <attribute alias="aggregate_column" name="revenue" aggregate="sum" />

          </entity>

        </fetch>

      </fetchcollection>

Is there any way to calculate percentage to display in charts of crm 2011 out of the box.

any help much appreciated..