The Atlantic Cities put the following heavy metal band density map together last year in an article titled Where the Heavy Metal Bands Are and the results are pretty much what you'd expect.
Check out those Nordic countries, woah!
I’m not really sure where or what that purple bit next to India is because I was educated in the American school system so if anyone can help me out, the comments section is yours and you’re be crowned internet king/queen of the hour. (Larger version here.)
Chief Editor and Writer for Metal CallOut. Favorite sub genre of heavy metal includes Black, Death, Folk and Traditional. Josh can be found at Google+.