I broke this down into two steps (easier for me to understand), you can probably combine then if you wish, but they're using different types of table calculations, so maybe not? I'm sure someone will have a more elegant solution, but this works.
1. Created a table calculation field called 'ProfitRatio-Totals' which (using 'Table (Across)' i.e. Order Date) just returns the totals for that year.
i.e. TOTAL([Profit Ratio])
2. Created another calculated field called 'ProfitRatioDifferences' - which uses 'Table (Down)',
i.e. [Profit Ratio] - [ProfitRatio-Totals]
Attached the sheet with this update.
Hi Fionnuala -
Thanks - I had actually figured this one out from another forum post...and your solution matched perfectly!