As for the reason why, I haven't any idea. I doubt that the percentage of left handed Canadians is statistically greater than among Americans.
I doubt that the theory advanced in the NPR story holds much water. All I can surmise is that since lefthanders are preferred at the positions of left wing and left defenseman, perhaps those young Canadians who don't do as well at those positions are moved to center ice or to the right side.
Not what you might think ... the story is about Hockey.
http://www.npr.org/templates/story/story.php?storyId=124129945&ps=rs
Attentive Olympic spectators may notice that most Canadian hockey players shoot left-handed, while U.S. players tend to shoot from the right. Why?
I confess I hadn't noticed, but then I don't watch much hockey.

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