To count for specific year items

Hi All

I like to count how many RAGs for a specific year, and this specifc year may varied as per user's request.  Please see the example below.  I would like to count the number of Red, Amber and Green based on the Year, e.g. 2023A, but user may also want to see 2023B or 2023C.  I wonder what is the best way to get the count?  Many thanks.