The Economist is quoting a research done by WHO – HBSC – Health behavior in School-aged children.
The research covers only the following countries (Japan is not included):
HBSC 2001/02, 36 countries: Finland, Norway, Austria, Belgium (French), Hungary, Israel, Scotland, Spain, Sweden, Switzerland, Wales, Denmark, Canada, Latvia, Poland, Belgium (Flemish), Czech Republic, Estonia, France, Germany, Greenland, Lithuania, Russia, Slovak Republic, England, Greece, Portugal, Rep. of Ireland, USA, Macedonia, Netherlands, Italy, Croatia, Malta, Slovenia, Ukraine.
HBSC 2005/06, 41 countries: The same countries adding Bulgaria, Iceland, Luxembourg, Romania and Turkey.
Belgium (French) is most violent while Israel is 24th, with 26% of 11 year old boys claim they were involved in at least 3 physical fights in the previous year.