Welcome to the community, @Keeran_Williams! :grinning_face_with_big_eyes: To do this, make a “Months” table, with the name of each record representing a given month/year combo; e.g. “Oct 2021”, “Nov 2021”, etc. In your existing table, link each record to the appropriate record from this [Months] table. Back in the [Months] table, add a rollup field that pulls in data from the appropriate field from your main table and tallies the values using the SUM(values) aggregation formula.
If your team members are collaborators in the same base, you could skip the [Months] table entirely and build something in the new Interfaces feature that displays the same info dynamically.