Pivot Tables - Calculate and filter

[AntMac]

I am trying to create a pivot table with Base data like this below. I am trying to now add a ratio of PM to demand and filter for assets where this ratio is high or low. I can get the table to display each percentage but every filter I try doesn't seem to work. Can this be down outside of adding additional columns with calculations in the source data?

Asset	PM/DM	Cost
One	PM	100.50
One	DM	200.75
Two	PM	25.65
Two	DM	35.80
Two	PM	46.90

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