Thanks for your reply David
I've been doing a bit of digging for statistics, most of which has been gathered in the US. This was some data collected by the Center for Disease Control and Prevention in the US. It has been documented here:
http://www.help4adhd.org/about/statistics
It highlighs some inetersting figures as it compares ethnic backgrounds, family structures, co morbidities, states, etc. There are definitely disparities between race, although not as significant as I previously thought, but even more interesting are statistics that show for example that there is higher prevalence of ADHD in families where there is no father than in a two parent household. Also that in children with other co morbidities the prvalence is high and so on and so forth.
