More people access higher education today than ever before. One in three adults in developed countries held a college degree in 2012, a substantial increase from 2000 when just over one in five had attained such qualifications.

According to data recently released by the Organization for Co-operation and Development (OECD), more than half of Russian adults held tertiary degrees in 2012 — the equivalent of college degree in the United States — more than in any other country reviewed. Meanwhile, less than 4% of Chinese adults had tertiary qualifications in 2012, less than in any other country. 24/7 Wall St. reviewed the 10 countries with the highest proportion of adults holding a college degree.

Click here to see the most educated countries in the world

The most educated populations tend to be in countries where tertiary education spending is among the highest. Tertiary education spending in six of the most educated countries was higher than the OECD average of $13,957. Spending on tertiary education in the U.S., for example, was $26,021 per student, by far the most in the world.

According to Andreas Schleicher, director for education skills at the OECD, education in the U.S. has become much more expensive, and student debt burdens have reached troubling levels in recent years. Despite these facts, it is still considered a good investment, as U.S. residents with higher degrees earn substantially more than their less educated peers.

It is also a worthwhile investment for the government. Schleicher explained that “taxpayers in the U.S. get $200,000 more out of every graduate than what they actually invested, so it’s a good business for the government as well.”

Despite the value of investing in education, there are exceptions. Korea and the Russian Federation both spent less than $10,000 on tertiary education per student in 2011, considerably lower than the OECD average. Yet, they still have among the most educated populations.

Qualifications do not always translate into stronger skills. While only 1 in 4 of U.S. college graduates reach the top-end of literacy skill, more than 35% reach that level in Finland, Japan, and the Netherlands. As Schleicher explained, “We typically describe people by their formal qualifications, but this data suggests that the skill value of formal qualifications vary considerably across countries.”

Nevertheless, countries with strong higher education systems tend to have higher levels of advanced skills. Roughly 12% of adults across the OECD performed at the highest literacy proficiency level in 2012. The percentage of adults performing at the highest literacy level exceeded that figure in five of the most educated countries.

Those higher skills may be paying off for residents. Only Ireland had an unemployment rate higher than the OECD rate of 7.5% in 2012. According to Schleicher, this relationship may also work the other way around because those who are employed are far more likely to pursue higher education and training. Unfortunately, this means “those who need life-long learning the most actually get the least out of it.”

To identify the most educated countries in the world, 24/7 Wall St. reviewed the 10 countries with the highest proportions of residents aged 25 to 64 with a tertiary education in 2012. These data were included as part of the OECD’s 2014 Education at a Glance report. The countries considered included the 34 OECD member countries, and ten non-OECD nations. Included in the report were data on the proportion of adults completing various levels of education, unemployment rates, as well as public and private education expenditure. We also reviewed data from the OECD’s Survey of Adult Skills, which included advanced adult proficiency in both math and reading. The most current figures for education expenditure by country are from 2011.

These are the most educated countries in the world.