Thank you -- this seems easy enough, but ....
Your first suggestion is to change the Column Value Formula to "Percent" (in my 4th column), but it doesn't like that, indicating I need a NUMBER.(perhaps because column 1 and column 2 are numbers?? [total sales])...so I used your alternate solution and entered -999. It seemed to like that fine.
Then I went to the next part of the solution (BTW -- how would we ever know that if we weren't asking experts like you -- this is not straight forward at all!!!). In the Currency X+2 formula I entered
if GridLabelAt("@InvoiceYr", CurrentRowIndex) = "-999" then "%" else ""
But it changed the format of the other 3 columns too -- NOT just the last column
*** My first 2 columns are based on a formula @InvoiceYr = toText(table.InvoiceDate,"YYYY")
This leads me to believe I've done something wrong in the 1st step.
Thanks in advance