Whatever the internet tells you about what is "standard"... as someone who has spent his life in New Zealand, I can assure you the majority of under-30s usually use "zee". "Zed" is on its way out.
It probably started with the popularity things like Sesame Street and Dragon Ball Z (Dragon Ball Zee).
However, interestingly, the one time everyone uses "zed" is when we acronymise the country name -- NZ, or N-Zed.
You've given a figure that is around a third of the entire population of the United States, so I think I'm on safe ground, even taking into account the Indian government's well known inability at accurate record taking, but thanks for the list, Pakistan has "187,758,480" under English speakers. No chance of them saying "zee".
