@onlmaps Knowing a lot of the history I can safely guess which parts they're thinking of. I'm a bit confused about France, though, unless 33% of the population wants to annex Monaco. Likewise for the Czech Republic, unless they want Lusatia (lost in the seventeenth century) and Silesia (lost in the eighteenth century) back.

@onlmaps Found the source

https://www.pewresearch.org/global/2020/02/09/nato-seen-favorably-across-member-states/#are-there-parts-of-neighboring-countries-that-really-belong-to-us

It's a pretty soft number, it's the percentage of people who 'somewhat' or 'completely' agree. Also people not expressing an opinion (i.e. "don't know" or some such) are not counted, and "in several countries, the share who did not express an opinion is relatively high".

Doesn't seem very useful.