If the Flow Efficiency is defined in Jira, then all you need to do is specify that this numeric field would be imported as dimension, and possibly as interval dimension, from eazyBI advanced settings: https://docs.eazybi.com/eazybijira/data-import/custom-fields/advanced-settings-for-custom-fields
If this field is calculated in eazyBI, then the logic should be brought out to JavaScript calculated field and that should be imported as dimension.
Lauma / support@eazybi.com