See Annex 3 for notes (wtvw.oecd.orgfedu/eag.htm). Education systems in OECD and most G20 countries now provide universal access to basic education, such that both pre-primary and upper secondary education are becoming universal in most countries (see Indicator C2). The expansion of upper secondary education has been driven by both increasing demand and policy changes ranging from a more flexible curriculum, a reshaping of vocational studies, and efforts to expand access to education to the entire population.