If we are to solve the biggest problems of our time — from climate change and food security to nuclear non-proliferation — we're going to need more scientists.

That's partly why the Organization for Economic Cooperation and Development (OECD) tracks new college degrees in 40 of the world's most advanced countries.

Now the group has released its 2015 Science, Technology and Industry Scoreboard report, which includes data up to 2012.

The ranking is based on the percentage of science, technology, engineering, or math (STEM) degrees awarded per capita, so that it's a fair comparison between countries with different populations. (For example, Spain ranked 11th by awarding 24% of its degrees in the natural sciences or engineering.)

Among the 10 smartest countries in the world Estonia occupies a high 7th place mostly because Estonia has one of the highest percentages of female STEM graduates, at 41% in 2012.