Pivot "% of Grand Total" changing

[heatherrink]

Dear Mr Excel - Please can you assist me. I have a pivot table where I have products shown with their market share calculated by using the "Show values as --> % of Grand Total" function on the pivot. My question is that when I deselect various products, this means that the true share changes because the pivot is using only what I have selected and is sharing it to 100% (ie A+B+C=100% but when you deselect A, B+C =100%).
Is there any way around this - can I deselect products without it affecting the % of grand total?
Thank you for your help

 

[nuked]

Sounds easy enough but I haven't been able to do it without some very ugly work around. I think you'd have to add a column in your source data to work out the percentage against total and simply add this as a column in your pivot. I can't see how you can get calculated columns or fields to ignore high level filters.