Grand total level of the percentage column giving value from the first row of column

Question

Hi Guys,
I have a requirement like to show the percentage value which the calculation of two columns , in the grand total level .
I think it can be achievaable by giving the aggregation rule for that column as Server complex Aggregate .
eg.
Fiscal Year  Department  subdepartment   Total cost     Sub Department cost     % cost
2011           Edu             Books                 500              50                               10
2011           Edu             Note Book           200            100                                50
2011           Edu             Furniture             300             30                                 10
2011            Edu                                      1000           180                              18
Grand Total
Ideally it should come like as above ..but the problem with me that ,it showing correct value for  all the rows ,but at the grand total level it's taking the value of % cost from the first row . like below..
2011           Edu                                   1000                  180                         10
Grand Total  
I have calculated the % cost column in the answer itself  as (Sub Department cost /Total Cost )
where the
Aggregation rule for the columns given are
Total Cost - Sum  ,Sub Dep Cost -  Sum, % Cost - Server Complex Aggregate
So plz suggest me any Idea to achieve this ..Thanks in advance.

Answer 1

Give the agg. as avg for % field.
Best of Luck,
Kashi