Country filter ridden / not ridden

The country filter as it is works mostly fine (apart from some values not being an actual country, and at least in the past, some countries appearing multiple times). However, to aid in completing the rider password, it would be helpful if the list were to be amended (perhaps at the top) with options for “ridden” and “not ridden”. Ideally as an extra filter (i.e., filter not ridden, then select your desired country).