over that period expenditure per student in primary secondary and postsecondary nontertiary levels increased in most oecd countries by an average of across the oecd with an average increase in expenditure of and a slight decrease in the number of students due to smaller cohorts reaching school age oecd however as noted earlier differences in the quality of education systems can lead to significant differences in the level of skills attained by people with the same level of educational attainment according to findings from the survey of adult skills the magnitude is such that university graduates from countries with lowperforming education systems have skills levels similar to those of students who have attained only secondary education in topperforming countries figure