Earlier quoted context omitted.
Even if respondents were unbiased and truthful. That sounds like a useless metric to me. You need a metric of the harm to society. Drug motivated violent crime for example.
Quote from the article: > Overdose rates have hit 12-year highs and almost doubled in Lisbon from 2019 to 2023. Sewage samples in Lisbon show cocaine and ketamine detection is now among the highest in Europe, with elevated weekend rates suggesting party-heavy usage. In Porto, the collection of drug-related debris from city streets surged 24 percent between 2021 and 2022, with this year on track to far outpace the las…
Much of Europe was locked down making travel often impossible. All that really says is there is a lot of drug tourism.