It is interesting to me to see (from Wikipedia, but there are lots of sources), that the population increase is less than a million from that time - they show 1950 as 7,891,957 (almost 8 million, as you say), but 2017 was 8,622,698. There has been a lot of upward growth in some buildings between those two dates, but perhaps the population density in each apartment has gone down, rather than increased. Something to find out some other time.