I am creating a spreadsheet that will contain cells with the following:

A, B, C, D, E
I need these letters to equal

5, 4, 3, 2, 1
So that when I create charts I can plot using the letters (gradescale).

so I could get data like a 3000 fence made of grade "A" materials will last say 5 years.

and that no matter what I plot the letters A,B,C,D,E will always equal 5,4,3,2,1.

How can this be done? Please help.

Thanks