Help on creating report grading calculation method

Hello all,

I'm trying to implement a grading scheme for graded reports I have in a sheet. The grades range from 1-5/A-E, and any report may receive one or more grades or none at all.

What's important is the number of grades each report has gotten, as well as the grades themselves. I want 1/A grades and 5/E grades to stand out prominently; namely, I want it to be obvious by quick inspection any report has gotten any 1's or 5's, and I also want to assess strength relative to other reports.

I want to weight the grades in some way, and a provisional method I have is to assign positive or negative points as follows:

1=7
2=3
3=1
4=-1
5=-10

Same thing with A-E.

Then I simply SUM the points. I also average the scores by the following formula, which ignores 0:

=IFERROR(SUM(range)/(SUMPRODUCT((range<>0)*1)),0)

Can I normalize/standardize via this grading scheme? Right now, it's not obvious to me.

I was also thinking of doing:

1=100%
2=90%
3=70%
4=50%
5=30%

But I don't know the relative merits, especially with weighing the scores and variable quantities of grades.

I'd appreciate any insight. Tks!