Plotting focused data against broad data

Hi All,

Hoping someone can assist with my enquiry.
I have a table of data that contains data specific to registrations that my team has completed.

I'm trying to be able to select a member of the team and plot their registrations count per month against the entire teams average registration count per month on a table.

I'm struggling with this because when I select a specific team member on my page's slider, all the graphs/cards information is filtered to that specific individual.

Is there any way I can calculate registration counts of an individual and for an entire group and plot them on the same graph?

Thanks and regards.