Building a pie chart based on % progress of parent task

Hello! I'd like to build a series of pie charts for a dashboard that show % complete of each group of parent tasks in one project. (Example: Entire parent task = 100%, completed tasks are 50%) The parent tasks would typically be either one level down (we have an overall parent task called "Project Summary", so would want to exclude this parent task) or two levels down (example: Project Summary > RFPs> Vendor X RFP). I cannot figure out the text mode reporting for this. I imagine I'll have to create a separate report for each pie chart to represent each parent task body of work.  

Thank you for your help!