At least 100 of the 'Living Legends' on Aidos originated from these few countries. But this did not mean that there were no Living Legends from other countries, just that they were not up to the 100 mark.
Now then, as for the Countries with the tag of 'Major World Power'; they naturally met all the previously mentioned requirements, and had at least 100 Living Legends, along with an extra 10 Sovereign Level Existences having originated from them.
There was a huge number drop when comparing the Legendary and Sovereign levels, but it could not be helped as Aidos' Sovereigns did not exceed a thousand in number.
They were once more than a thousand, but a certain powerful human's rampage more than 2 decades ago wiped out nearly all the Sovereigns from a particular race, reducing the overall number below 1000.
For a planet with a population in the billions, this was an exceedingly small number, even when compared to the number of Legendary levels.