Interesting stat from the New York Times, circa 2010: "According to sales figures from stick manufacturers, a majority of Canadian hockey players shoot left-handed, and a majority of American players shoot right-handed."
One theory for why Americans are more likely to shoot right-handed--they're more likely to pick up a baseball bat as a kid (which typically involves left hand closer to the end of the bat, on the bottom), which makes shooting right-handed feel more natural.
This is what I think as well.
I am right handed but I shoot left, bat left and golf left. I was already skating by the time I was 4 years old and playing organized hockey by the time I was 6.
Suffice to say, I was skating and using a hockey stick long before I picked up a bat and a glove.
I played hardball as a kid and then softball for most of my life.
What I think really proves this point is when I have participated in puck/ball tournaments.
For those that have never heard of these, it's simply a tourny that has both hockey and softball games with a capped number of players allowed with a certain number of them that have to participate in both.
Compared to my regular softball league(s), these tournies always have a high amount of left-handed batters.
In my regular league(s), you see maybe 2-3 lefty batters per team, if that.
In those tournies, it's more like half and even more sometimes.