Re: Small change if earth's yrly GDP / earth's population
Also, I think one thing people fail to realize when talking about global income levels is that the cost of living isn't the same everywhere, and it isn't necessarily completely accounted for after converting from whatever currency is under question to the dollar.
I live in France, for example, and 1 Euro is worth 1.315 Dollars, so one might naively expect that the cost in Euros of living here should be less than the cost in Dollars of living in the US, but in fact the number of Euros required to live for a month comfortably in France is actually equal to or more than the number of Dollars required to live at the same standard in the states.
In other words, even after doing standard conversions between currencies, the "real value" is still obscured. So it's not exactly immediately clear what the data in the OP actually tells us -- all it tells us is how many dollars the average person makes, but that actually tells us quite little, I think, about the actually relevant details, like quality of life etc.
In certain poor places, for example, where people work for some amount of money that, when converted to dollars, most Americans would find horrific -- in fact that horrifically low income can often, because of local food prices and things like that, provide actually a fairly comfortable standard of living. Maybe they don't have internet, maybe they don't go to the movies as often as their American counter parts, but they eat well.
So, it's a bit more complicated, I think, than just taking the worldwide GDP and averaging it out.