My client has a standard report which shows monthly figures for various sales, enquiries etc. The report shows all months since the start of the contract (about three years ago, but growing by 1 every month!). The last row in the Tablix shows the totals (essentially the sum of all cells in that column above).
They have asked me to introduce another couple of rows, showing Year To Date values, for totals and monthly averages. I feel sure that there must be a way to do this simply (essentially it is the SUM or AVG of the last 12 rows in the Tablix), probably through grouping, but I just can't get my head around it.