Answer:
HDI-human development index
the colum below shows schooling years(education part of HDI)-shows how "intelligent" a country is which indirectly relates to how much income is earned.
A very large range of countries are shown and as the poorer the country gets so does the level and amount of education
Step-by-step explanation:
HDI is is a statistic composite index of life expectancy, education, and per capita income indicators, which are used to rank countries into four tiers of human development.