How to get a report including people who left the organization?

I need to create a report of all billable work by client for this year and I have a problem doing that because I doesn't look like I can include people who don't have a license anymore.  I have 3 people who left my team and I can't have them in my report if I want to know also how much each team member contributed on the billable of the project.

Is there a way to do that?

Thanks