dear Sara,
I can recommend reading the following article regarding research on Dutch children.
http://download.journals.elsevierhea...7610005998.pdf
Most children in Holland are caucasian (80%), but our population is a colourful one. We do have a large number of North african, European, Caribbean, Indonesian, Turkish, Maroccan inhabitants as well.
Have a look at the following site.... http://www.psych.nyu.edu/adolph/
Karen has publised an enormous range of very interesting articles.
This one is about the differences in cultures http://www.psych.nyu.edu/adolph/PDFs/CultureChapter.pdf enjoy!
I do not know of any other publications with scores for different ethnicities as you have asked. Maybe you could take a peek at the WHO site and find more information there.
Esther