I often see comments that appear to indicate that, whoever posts them take for granted that the readers are within USA. I do believe that many readers and users are international, I am. It would help if more keep that in mind.
I don't know if dang has published generalized region stats for HN. You could email the moderators to see if that is something they do / have done / would do.
hn [ at ] ycombinator dot com
My guess is that a majority are in the U.S. and some in E.U. based on posting and reply times.
Although I want good content, wherever the authors and their ancestors might be from, I can't help but feel a bit refreshed to see people from all over the world and all walks of life end up in the top of HN.
USA: 60%
Rest of America: 5%
Europe: 15%
Other: 20%
(That's why we get a post about the Super Bowl in the front page each year.) YYMV. Hi from Argentina!