Returning list by group by

I created a list, where my system shows me every winner to a Formula 1 Grand Prix. Such lists can be very long and I want to make it a bit shorter but I don't know how I can do it.

In my example, you can see that every winner will shown as single. I want for every winner who has only one win will be shown in a list like '1 name, name, name' and for the next ones who has two wins, three wins and so on.

I get all results from my table for results and it will grouped by the id of the winner.

What I can do in my foreach loop? example

via Chebli Mohamed