Annual expenditure per student on primary to tertiary educational institutions provides an assessment of the investment made in each student. In 2020, the average annual spending per student from primary to tertiary education in OECD countries as a whole was around USD 12 500. But this average masks a broad range of spending across OECD countries. Annual spending per student ranged from around USD 3 200 in Mexico and USD 4 500 in Colombia to over USD 26 800 in Luxembourg (Table C1.1). The drivers of expenditure per student vary across countries and by level of education: in Luxembourg, for example, low ratios of students to teaching staff and high teachers’ salaries at primary and secondary levels (see Indicator D3) are reflected in high levels of expenditure per student. In contrast, Colombia has one of the highest ratios of students to teaching staff, which tends to drive costs down (see Indicator D7). These differences can also be attributed to the diverse levels of Gross Domestic Product (GDP) and national wealth, with Colombia and Luxembourg representing the opposite ends among OECD countries (see Indicator C2).