Unless you are throwing in history and including all of those Roman senators who received what is by todays standards practically nonexistent medical care (I th

Unless you are throwing in history and including all of those Roman senators who received what is by todays standards practically nonexistent medical care (I think that doing that would be a mistake, for reasons that should be obvious), then it is somewhere around 10-15% of the world's population that lives in developed countries. This is before we even consider that many developing countries have functional healthcare systems. The population of Germany alone accounts for more than 1% of all currently living humans.