Over that period, expenditure per student in primary, secondary and post-secondary non-tertiary levels increased in most OECD countries (by an average of 19% across the OECD), with an average increase in expenditure of 15% and a slight decrease in the number of students (3%), due to smaller cohorts reaching school age (OECD, 2014). 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 low-performing education systems have skills levels similar to those of students who have attained only secondary education in top-performing countries (Figure 1.1).