Trouble creating calculated column


I am having following issue while trying to create a calculated column. 

I have a column (lets say 100 rows) which has only two values either "Y" & "N". When I create a pivot in excel, I can add this column to "Column labels" and I will get 3 columns - "Y", "N" and "Grand Total". From here, I can do calculation like Grand total/Y or Grand Total/N. But I can do this in Spotfire.

Can I do a calculation like this in Spotfire or is there a way I can split the column and then do a calculation? Please check the screenshot for reference. 


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