For the last couple months, my partner and I have been scouting for a small and cosy apartment in the suburban upmarket neighbourhood of Bandra, Mumbai.

We have regularly come across the term ‘expat housing’, where rentals range from 200,000 to 1 million rupees ($3,000 - $15,000) per month. This amount is exorbitant for most locals: in Bandra, an average one-bedroom apartment rents for around 50,000-100,000 rupees ($750-$1,500) a month. But it is far from uncommon in areas such as Bandra, Worli and Breach Candy, prime residential areas on Mumbai’s western coast that have their fair share of cafes, restaurants, malls, and pubs.

And living in those desirable neighbourhoods of Mumbai are some of the best-paid expats in the world.

“I’ve heard stories of expats who would get huge allowances in the range of 1-1.2 million rupees ($15,500-$18,500) per month just for housing,” says Colin Walker, a former banker who recently moved back home to the US after a seven-year stint in India at two multinational banks. “Senior-level expats expect to be provided with a house of the same standard as theirs back home,” he adds.

What kind of salaries must expats earn in Mumbai to afford such expensive housing? More than $200,000, according to new survey data from HSBC which found Mumbai expats to be among the highest-paid in the world.

This week, HSBC released new salary data from its 2017 Expat Explorer Survey, drawing on responses from 27,000 foreign workers in 159 countries. The survey found Mumbai expats earned an average of $217,165. The global average wage among expats sits at $99,903, while expats in San Francisco and London weigh in at $207,227 and $107,863 respectively.

How can it be that expats in Mumbai earn so much more than the global average?

Older, more experienced workers

Dean Blackburn, head of HSBC Expat, says Mumbai had the highest percentage (44%) of expats sent by their employer. “These expats often benefit from relocation packages, which goes some way in explaining the higher salaries expats enjoy in the city,” he says. He added that employment for expats was very high in Mumbai (89% versus the global average of 78%) and many work in engineering.

Age may well have something to do with it. For example, the survey found 52% of the expats in London were millennials. Mumbai’s expat workforce is older: 54% were aged 35-54, compared to the global average of 45%. Clearly, expats in Mumbai seem to be older and more experienced.

Read more on bbc.com.