Table 2

Summary of the included studies by country

CountrySexAges (years)Sample sizeCountry–sex–age–year groupsSpan of years
Australiaw1–w12 Boys+girls9–1625 9611011988–2010
Belgiumw13–w23 Boys+girls9–1723 3581171985–2010
Brazilw24–w26 Girls9–172826241998–2006
Canadaw27–w32 Boys+girls9–1729 009911981–2011
Estoniaw21,w33–w38 Boys+girls10–177906461992–2002
Francew18,w39–w45 Boys+girls9–145763321985–2007
Greecew18,w46–w50 Boys+girls9–17268 382551991–2014
Hungaryw18,w21,w51,w52 Boys+girls12–172455221990–2013
Italyw18,w53–w58 Boys+girls12–175218311986–2007
Japanw59–w75 Boys+girls9–17279 7323061998–2014
Lithuaniaw34,w35 Boys+girls11–176479281992–2002
The Netherlandsw76–w78 Boys+girls12–163457221987–2006
Polandw79–w82 Boys+girls13–1722 895191992–2007
Portugalw83–w89 Boys+girls9–1729 857711999–2011
Seychellesw90,w91 Boys+girls11–167913241990–2004
South Africaw92–w99 Boys+girls11–162668301996–2012
Spainw18,w100–w112 Boys+girls9–1725 9501511985–2010
UKw113–w126 Boys+girls9–1648 5351161986–2014
USAw127–w137 Boys+girls9–17166 9001221995–2013