Pie Chart with Avg

Hello, I am trying to implement a Pie Chart with the sample data below. Legend: Color and Values: Average of Days. The problem is that there are records that have the same color mutilpe times so when it does the average for yellow below it is (5+7+14)/3. I want the color average but the color should be grouped by the ID. So, (5+7+14)/2. How can I accomplish this?  Thanks!