evidence: In 2017, OECD countries spent an average of 4.9% of their gross domestic product (GDP) on educational institutions from primary to tertiary levels, with wide variations across OECD and partner countries. On average, the share of national resources devoted to non-tertiary education (primary, secondary and post-secondary non-tertiary levels) was 3.5% of GDP, much larger than the share devoted to tertiary education (1.4% of GDP). [...] Tertiary education accounts for 1.4% of GDP on average. At this level, the various pathways and programmes available to students, the duration of programmes, the organisation of teaching, and research and development (R&D) activity all influence the level of expenditure. In 2017, Australia, Canada, Chile, Norway, the United Kingdom and the United States were the countries that spent the largest share of GDP on tertiary educational institutions (2-3%). Unsurprisingly, these countries also have some of the highest levels of expenditure from private sources of educational funding after public-to-private transfers have been accounted for (1.1-1.7% of GDP) (Table C2.2 and Figure C2.2).