chart question

I want to be able show the numbers on chart incrementally. For example,
where if i have the values as 2, 5, 8 on chart, I would like to show as 2,
7, and 15 .. and so onâ?¦ can you help me with this please?
This is my formula for the chart â?¦
=Sum(Fields!NumberOfCrs.Value)
Thank youDid you try runningValue function?
like
=runningValue(Fields!NumberOfCrs.Value,sum,"chart1_SeriesGroup1")