Need to show sum of column value at end rdlc file?

I'm working on rdlc file getting values from stored procedure from that i have created dataset to show all values on rdlc file.

Need to show AVG of column value at end rdlc file how to do this?

I tried with AVG aggregate function using expression but problem is how to group by my column ?

guide me. 

Ashish Fugat (ashuthinksatgmail.com) SE