I'd flip the question around, and ask: For the average person to have a reasonable standard of living, let's say within an order of magnitude of what I have, a

I'd flip the question around, and ask: For the average person to have a reasonable standard of living, let's say within an order of magnitude of what I have, and assuming that there are variations within this (e.g. some are poorer, some are richer) - How many people can we support before we have to start heavily rationing?