You could handle this by hiding the others, but it's not very dynamic:

The other way to do this is a filter that uses a table calculation - the table calc filter is applied after the sum percent calc,so the % remains correct.

Create a calc field:

lookup(attr([Fc Rc Elpa],0)

and drag this to the filter and select whoever you want to.

This table calc basically looks up the FC Rc on the same row (0), so while a table calc, does absolutely nothing...

Read the last post first...

And:

total is: total(sum([Number of Records]))

You could drag these to the level of detail for them to appear in the tooltip:

Put the real categories pill into the filter as well and exclude them.