Finland most selective …

„Among OECD countries that were imposing specific entry criteria in 2016, Finland was the most selective with 67% of applicants rejected, compared with an OECD average of 30%. […] Only 25% of upper secondary graduates manage to continue their tertiary studies immediately after graduation, and the average age at which Finnish students enter tertiary education for the first time is amongst the highest in the OECD.“
OECD (Hrsg.), „Investing in Youth: Finland“ (2019), S. 55