I assume you want a percentage as compared to the other bar within the same category, right?  If I take your chart in the screenshot as example, the first bar should show 10%, the second one 90%, and so on, right?

To get that done, you can actually calculate it through an expression that references the actual category group in the chart.  In your case that would be something like this:

=Count(Fields!ID.Value) / Count(Fields!ID.Value, "Chart1_CategoryGroup")

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The first part (in front of the / division operator) gets the count of the current series item within the current category while the second part gets the count of all items, regardless the series, within the current category item.

To get your value formatted right, put something like 0% in the Label > Format property of the Chart Series (can be done through the Properties window).

In case you're interested in learning a bit more about the formatting options: Formatting Numbers [SSRS]

Thank you so much for all your help. Finally I was able to show the percentages. I have issue with the formatting. Please see the attached screenshot. I have used FormatPercentage in Series Label properties. =FormatPercent(Count(Fields!ID.Value) *100/ Count(Fields!ID.Value, "Chart1_CategoryGroup")). I am new to ssrs and I am not sure where to format it. Could you please help me on this. I am in hurry to complete this task.
Chartscreenshot.png

Thank you ValentinoV for all your help. I truly appreciate it.  You saved my day. I removed 100 in expression and it worked. Is there anyway that I can increase the space between bars for more clarity.

Ok let me give a try  in setting the point width thanks again

Sure will do . Thanks for all your help