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Please note that some countries (e.g. US, UK, South Africa) have racial/ethnic census data, while most counries don't and some (France) even forbid collecting such data. These numbers are all just estimates, which is also why I decided not to put the percentage labels into the graph.
Please also note that for the US, I used the number of non-Hispanic whites. This is roughly comparable with "people of European descent", however it excludes Hispanic whites and includes the Middle East and North Africa. If Hispanics are included, some cities such as Miami or Los Angeles would have higher percentages of 'European-Americans'.
All the cities included were founded by Europeans/whites and have had a European/white majority. Even in Constantinople (which was conquered by the Muslims in 1453 and renamed to Istanbul in 1930), a third of the population was Greek until the genocide in 1919-23.