Only display unique value

Here is an interesting conumdrum. In this data here we have some Employees who have achieved  various skill levels against various skill types. The Skill types are not included here. What we are  trying to do is count the number of staff at their highest level but no at any other level.

So the count for this data would be

Level 4 = 1 (only Fred - his highest level))

Level 3 = 2 (George & Henry - their highest level

Level 2 = 0 (George, Henry and Fred already counted at the highest level)

Level 1 = 0 ((George, Henry and Fred already counted at the highest level).

Any ideas of what the calculation would look like?? - trying for a funnel chart