I want to be able to gauge how well users are at picking up calls originating from call queues.

For instance, let's say John is on the phone 5 out of 8 hours in a day. In those 3 spare hours 20 calls come in that he isn't picking up. Would there be a report or a KPI that would measure this? What I'm trying to find out is which users are being most productive with their time and which ones may be avoiding calls.