How to Use the 'Result' line to caculate a special value?

Hi experts:

For example,the dimension is product (a ,b c ,d),and key figure is revenue,

then I want to show the value -->the percentage of the revenue of each product .

so that's the problem , how I can get it,or how i can get the sum of all products.

can I get it from the result line or is there a better way to get it?

thx

chan