Reader's Digest conducted this global, social experiment. Source: www.rd.com/culture/most-honest-cities-lost-wallet-test/
Reader's Digest put a name with a cellphone number, a family photo, coupons, and business cards, plus the equivalent of $50, and "dropped" 12 wallets in each 16 selected cities - in parks, near shopping malls, and on sidewalks.
Population figures are inside city limits, suburbs not included, source Wikipedia;
Region is a hint: EU North means EU location north of Germany, EU South means location south of the Alps, etc...