The US compares relatively well because, despite having comprehensive education, the system is also designed to segregate schooling areas.
In Europe, bullying is worst in countries with comprehensive systems (UK/Nordics/Eastern Europe, unsurprisingly they are countries that have left-wing education systems built for the social justice goals of adults, not learning outcomes of kids). I believe it is as bad or worse in Asia although for different reasons.
Btw, there are also quite good stats about sexual violence against girls and, unfortunately, you actually see these levels are highest in comprehensive systems in Europe. This is likely due to under-reporting elsewhere but it is very strange to see somewhere like the UK come out worse than Afghanistan in violence against girls. I think people should also ask why this kind of stuff isn't known (again, it is because schools are designed for social justice for adults, not for kids...it is an unfortunate reality of our world).