I have developed similar reports but they are dependent on routing strategy. There is a routing path with associated virtual queue for each skill. So to report for each skill independently I need to get statistics for needed queue.
You need to create virtual Agent Groups in the CME. In such a Group you can add Special Skills and Levels.
You can have for example a group containing Agents with a skill of English > 5 but no Spanish. You can also use this groups for Routing and Display in CCP