GDP per capita is the most-used single measure of a country's average income. Luxembourg, Switzerland, Ireland, Norway, and Singapore all sit above $80,000 per person; Burundi, South Sudan, and the Central African Republic sit under $500.

Petro-states and microstates

Monaco, Liechtenstein, and Bermuda are off the chart but excluded from many rankings because they're not full UN members or report differently. Qatar and the UAE punch above their weight thanks to oil and gas. Ireland's figure is inflated by multinational accounting — Apple's European HQ being there. Equatorial Guinea has a huge per-capita GDP and one of the largest inequality gaps in the world.