Always rational, 100% of the time! Isn't that one of economic's founding assumptions? 
What are you doing in New Zealand? You should be at the University of Chicago with Robert Lucas. The ranks of the Rational Expectations and Efficient Market Hypothesis disciples have become rather thin in the last 2 years for some reason. :P
I don't see any negative or positive correlation relating to maths usage really, so perhaps the half of the world that buy Xbox 360s are foolish and the other half which buy PS3s are not? The Wii buyers are just kicking to a trend.
Before someone jumps down my throat, I'd like to emphasize that was not a serious statement.
However, I can't help but point out that your link definitely shows a correlation. Notice how Japan and various continental european countries tend consistently beat out the US, UK, and Australia?
