I have a formula that I am trying to create. I have 8 categories which make up a section of a grade report for employees. Each category is weighted differently with the highest weighted total being 25% and the lowest being 5%. I am trying to figure out how I can decrease the weighted totals from 25% to 5% evenly so each decrease is of an equal amount. As of right now I came up with 2.85%, but the problem is, I cannot have the whole equal more than 100%. This is what I have so far:

25%, 22.15%, 19.3%, 16.45%, 13.6%, 10.75%, 7.9%, 5.05%

The problem is when you add up all the percentanges, it equalas 1.2. Please help.