by GDP-PPP per capita

But what do we mean when we say a country is “rich,” especially in an era of growing income inequality between the super-rich and everyone else? While gross domestic product (GDP) measures the value of all goods and services produced in a nation, dividing this output by the number of full-time residents is a better way of determining how rich or poor one country’s population is relative to another’s. The reason why “rich” often equals “small” then becomes clear: these countries’ economies are disproportionately large compared to their small number of inhabitants.

However, only when taking into account inflation rates and the cost of local goods and services can we get a more accurate picture of a nation’s average standard of living: the resulting figure is what is called purchasing power parity (PPP), often expressed international dollars to allow comparisons between different countries.