General SS help

Good evening all, attached is a spreadsheet that shows players at different age groups and the games they have played for a local football team.

I would like to try to use the data to show the movement there has been between the different ages groups. For example how many U16 players have played for the U17’s team.

Obviously I could just look across and do it manually but was wondering was there some way to put in a formula that could do this and display in a chart of some sort automatically as the data is updated.

Thanks in advance for any help / suggestions.