Europe is Sony's largest market, by far.
Would you be so kind as to detail how you arrived at "largest market". I won't even comment on the "by far" bit. It might also help if you could clarify what you are defining as "Europe" since there are many different classifications that are thrown about.
I'm pretty sure I recall a GAF breakdown which suggested that for Sony the US was slightly greater than a 50% share for both hardware and software.