So here's a stat for you. In the past half century, the population of the world has slightly more than doubled – from 3bn people in 1960, to around 7.1bn in 2013. But over the same period, the number of people switching countries has nearly tripled, from 77m in 1960, to 232m in 2013.
In other words, not only are there more migrants in today's world: they make up a higher proportion of the world's population, too.
People move from one country to another for many reasons: work, love, to escape people who are trying to kill them. But one thing that migrants the world over have in common is that they generally end up in cities, where economic opportunities are greatest and they're more likely to find people form their own country.
But, as the chart above shows, there are quite substantial differences in the proportion of different cities' populations were born in other countries. The figures come from the International Organization for Migration, and the chart was made for us by Statista. (It isn't a comprehensive top 14, incidentally: it's just a selection of cities.)
In 2014, at least, London and New York, both housed populations that were around 37 per cent foreign-born. These are the two unchallenged "world cities", hubs of cosmopolitan life, so one might expect them to be near the top of the chart.
Not a bit of it, though. Los Angeles and Sydney are both effectively in a statistical tie with the big two. So is Singapore, even though it has an advantage on this ranking (as a city-state, anyone who doesn't come from the city itself counts as a migrant).
More surprising are some of the cities at the top of the chart. Auckland, the largest city in New Zealand, has more foreign-born residents than London. (That said, one suspects these will disproportionately come from one country of origin – the UK – so whether that makes it "cosmopolitan" is a different question). Toronto, meanwhile, is home to substantially more foreigners than London or NYC: a reflection of a relatively easy going attitude to immigration, perhaps?
The two cities at the top of this chart are perhaps more explicable. Brussels is the de facto capital of the European Union, as well as the home of NATO; the whole city's economy is based on being a place where foreigners can meet up and argue with each other in a proximity to a decent restaurant.
Dubai, too, is a city whose economy has been built on attracting foreign Labour, but in a very different way. Only around one in six of the city's population come from the UAE. An even smaller slice – perhaps as few as one in 30 – are from western countries.
In fact, the city's population is overwhelmingly drawn from the countries of Southern Asia: India, Pakistan, and Bangladesh. And a full quarter of Dubai residents are thought to come from just across the Strait of Hormuz in Iran.