A short summary of the results:
http://www.businessinsider.de/pisa-worldwide-ranking-of-math-science-reading-skills-2016-12?r=US&IR=T
Oecd homepage with much more infomation:
https://www.oecd.org/pisa/
South east asia is dominating the rankings again (singapore, hk/china,japan, south korea)
Interesting is that east europe mostly underperforms oecd average.
The USA saw a huge decline in maths.
Saudi Arabia even though very rich underperforms by a lot in relation to oecd average.
Very interesting is also the result of vietnam:
Like in the last pisa test they ranked pretty high outperforming oecd average in maths (22th) and science (8th) even though their economy is nowhere near the similar scoring nations.
A fact that is even more weird if you think about the flynn effect and its implications.
Edit
The test was in 2015 but results just came out.