How to make evolutions in pivot table with multiple column labels

Hi all,

I got stuck while creating a reporting tool in excel, I tried to google the solution, but without luck. I would like to kindly ask you for your expert help on this issue, I'll be glad for any ideas how to solve this. Please find attached an example of the file(example.xlsx) and what I would like to achieve (evolution.jpg).

Objective:
Reporting tool - User should easily browse through different Business units, clients, products and see P&L evolution per month/year in absolute(value) and relative(ratio, vs gross sales)
Issue:
I am not able to do a calculated field in the pivot which has more column lables, I don't know how to do this when I can't use references/names/arrays etc.

The database has up to 250k rows so using formulas to calculate the evolutions within the database is I think not a good option. Unfortunately I am not able to extract the evolutions from our company's system. The only way what I thought would work is the calculated field option.

I would really appreciate any ideas.

Thank you very much!

P.