The only study on this subject I'm aware of is the one funded by The Ocean Cleanup Foundation [1], which puts 86% of annually released plastic in Asian rivers,

The only study on this subject I'm aware of is the one funded by The Ocean Cleanup Foundation [1], which puts 86% of annually released plastic in Asian rivers, with the main contributor being the Chinese Yantze river, followed by the Ganges. This compared to a mere 0.28% and 0.96% for Europe and North America respectively. They've also released an interactive map [2], although if you're just interested in the numbers I'd recommend reading the paper. [1]: https://www.nature.com/articles/ncomms15611.pdf https://www.nature.com/articles/ncomms15611.pdf [2]: https://www.theoceancleanup.com/sources/ https://www.theoceancleanup.com/sources/