Measuring drug-use is a tricky pursuit, because it's not exactly a subject that inspires a lot of honesty. But now, thanks to modern science, we've got a much clearer picture of drug use in different cities. It turns out that Londoners have once again shown their propensity for cocaine in comparison to the rest of Europe.
However, London's not quite managed to nab the top spot this year according to a joint study by the SCORE group in association with the EU drugs agency (EMCDDA). Whilst the UK's capital had the highest proportion of cocaine use in 2015, this year it's been overtaken by Belgium's own Antwerp. Zurich, Barcelona and Molina de Segura complete the top five cities for cocaine in 2016.
What's particularly interesting is the fact that even though the study shows that Antwerp has the highest cocaine use, this is just overall - and it is apparently Londoners who take the most coke mid-week.
To be precise: on average in Antwerp 1,042mg of coke is taken per 1,000 people per day, whereas in London it's 999.3mg per day. Compare this to the average weekday, where it's 790.5mg per 1,000 people for London, and 745.2mg in Antwerp.
Cocaine use in London has stayed pretty much the same from 2015 to 2016: it is Antwerp that has vastly jumped up, instead of Londoners steering clear of the drug.
And FYI: this is just for coke, which seems to be particularly popular in London. The city doesn't even make the list for the other drugs the EMCDDA tested for (which were amphetamines, methamphetamines and MDMA).
So, how do we know all this? Sending out a few questionnaires would be unlikely to provide particularly accurate results. Instead, scientists have come up with a far more precise method: by testing wastewater. Not exactly the most glam of jobs, but someone's got to do it (we're just glad it's not us). It's called wastewater based epidemiology, if you wanted to get fancy about it.
If you're interested in the nitty-gritty of how it all works, take a look at the explainer video.