Rising educational attainment is most strongly reflected in the increases in tertiary attainment rates over the past few decades. On average across OECD countries with available trend data, the share of 25-34 year-olds with a tertiary degree (i.e. short-cycle tertiary, bachelor’s, master’s or doctoral or equivalent) has increased from 27% in 2000 to 48% in 2021 (). These increases mean a tertiary qualification has become the most common level of attainment among younger adults on average across OECD countries. If current trends continue, tertiary attainment will overtake upper secondary or post-secondary non-tertiary attainment as the most common level of educational attainment among the entire working-age population in the near future as the current group of 25-34 year-olds age and younger cohorts with higher levels of tertiary attainment enter the workforce. Tertiary attainment is already becoming the norm among young adults in many OECD countries. In 14 OECD countries, more than half of all 25-34 year-olds have a tertiary degree, rising to at least two-thirds in Canada and Korea. Italy and Mexico are the only OECD countries where tertiary attainment among younger adults is below 30% ().