How To Create A Percent Of Variance Column In A Matrix

I have used SSRS 2005 to create a matrix and need to add a % of variance column. Is this possible? I hope I'm missing something simple. Basically the report should look like this:



Item CurVol PriorVol % of Var CurSales PriorSales % of Var

abc 100 90 11% 1250 990 26%

cde 96 128 -25% 192 243 -21%





Dataset looks this this:



Select item, vol, sales, 'Current' AS Per

FROM Table
WHERE (invoice_date >= @curStartDate) AND (invoice_date < @curEndDate + 1)
UNION

Select item, vol, sales, 'Prior' AS Per

FROM Table
WHERE (invoice_date >= @priorStartDate) AND (invoice_date < @priorEndDate + 1)



The column group on the matrix is using the Per column because the accounting periods cross over calendar months.





gusina