Perform a calculation, and put the values into single value fields

We are currently doing a yearly savings calculation in Jira that we want to occur within EazyBI in order to saving some memory and processing. From what we understand, we need to create single value custom fields within EazyBI that will store this data as well as retain historical data, and we have the JavaScript that performs the calculation. What I need help in understanding is how do we get the calculated values from the JavaScript into the single value fields without performing the calculation in each field?

The custom fields we’re creating in EazyBI are Mon Yr, so we’ll be creating a few dozen to account for all of the data that we have, and it will be pulled in from several projects.