
By default an SSRS chart does not display a label on the chart.
In order to display them, right click on the actual chart and enable “Show Data Labels”.
The problem is how do we display a numeric value as a percentage to the total values?
Firstly, select the label and go to the Label properties and change the UseValueAsLabel property to “false” and Label property to ”#PERCENT{P0}” for whole number values or “#PERCENT{P1}” for decimals.
Check the technet article (http://technet.microsoft.com/en-us/library/dd239373.aspx)