Next to that, Iq doesn't mean shit at national lvl. .
And well, US has been "importing" a lot of talents (how many immigrants have come to the US during the last century?). Not to mention this is about "average". Certainly you have many of the brightest in the world but if you are talking about average, I think you are wrong to think US and Canada should be anywhere near the top or above the "norm".
Does it surprise you that you get flamed when you call other nationalities, and indirectly their inhabitants stupid? So yup, you deserve to get flamed.