In Luxembourg, Mexico and the Netherlands, the pro-male gender gap shrank because boys performed more weakly, while girls stayed steady. However, comparisons between the performance of 15-year-old students in OECD PISA in 2003 and the performance of roughly the same birth-cohort at around age 24 in the 2012 OECD Survey of Adult Skills (PIAAC) suggest that gender gaps in mathematics sometimes widen as teenagers move into adulthood (Figure 6.3). Among OECD countries with available data, the average standardised gender gap is 0.12 points at the age of 15, and 0.18 points at around age 24 - still only small. However, in Canada, Austria and Norway the standardised gender gap among those aged around 24 is greater than 0.3 points, and in Finland and the United States it is larger than 0.5 points (Figure 6.3).