Percentages for skills matrix

Not entirely sure how to explain.

So basically, I have a spreadsheet with fellow staff members and their skills with ratings.

1 = Not Yet Qualified
2 = Basic Skills
3 = Intermediate Skills
4 = Advanced Skills
5 = Highly Advanced Skills

So in column A, i have a list of tasks, and along row 1 all the staff names. I place the relevant number into the column with the staff name on row of the skill.

In another part of the spreadsheet, I have a formula (=COUNTIF(B:B,1) and all the other numbers) which calculates how many times the number appears.

So far up til this point everything works the way I want.

The next part is where my brain won't work and figure something out.

I want it so that the total number returns a percentage based on how high the numbers go.

Example: (to make it easy, I'll base this on 10 questions, in reality there will be a much larger number, i.e. 104 or something) My maths is bad so i'm just going to make up the percentage results.

If "Steve" is a 5 in all skills, the percentage would be 100%.
If "Steve" is a 5 in all except one skill where he is 1, the percentage is 90%.
If "Steve" is a 1 in all skills, the percentage would be 0%.
If "Steve" is a 1 in all except one skill where he is 5, the percentage is 10%.

I want the percentage to reflect the rating and the combined total of questions answered. I know what I want in my head, but trying to explain it is hard.

I've attached a dummy version of my spreadsheet.