Those are of course the hypothetical upper limits.
I doubt there are sufficient people with those citizenships who meet the age requirements who can apply.
On the other hand, I wonder if the UK should offer a certain number of Youth Mobility visas to the EU en bloc.
True that it is not freedom of movement, but if some youngsters want to reside in the UK on a short-term basis, it may be an option.
Adding the link to the
Tier 5 visa forum here for anybody in future who may have questions about eligibility for application, etc.
I am not a lawyer or immigration advisor. My statements/comments do not constitute legal advice. E&OE. Please do not PM me for advice.