Okay here's the breakdown. Those I marked "aliens" go wherever they damn well please, so I didn't put them under any one country. Also, I skipped the Blackhawks, Legion Lost, and the Legion of Superheroes, because I have no idea who the hell those characters are so I couldn't determine citizenship.

USA - 45
Aquaman (Atlantean), Wonder Woman (Themescaran), Superman, Green Lantern, Batman, Flash, Cyborg, Mister Terrific, Hawkman(?), Guy Gardner, Booster, Green Arrow, Firestorm (Jason), Firestorm (Ronnie), Captain Atom, John Stewart, Kyle Rayner, Batgirl, Arsenal, Red Hood, Nightwing, Ivy, Black Canary, Catwoman, Batwoman, Voodoo, Swamp Thing, Animal Man, Resurrection Man, Red Robin, Superboy, Kid Flash, Static, Hawk, Dove, Midnighter, Apollo, Jonah Hex, Sgt. Rock, Deathstroke, The Grifter, Blue Beetle, Harley Quinn, Deadshot, King Shark

Europe - 1
Frankenstein

Britain - 5
Madame Xanadu, John Constantine, Etrigan, Andrew Bennett, Vampire lady(?)

Norway - 1
Ice

Russia - 1
Gavril

Africa - 2
Vixen, Batwing

Middle East - 1
Robin (has dual American citizenship due to Bruce)

Brazil - 1
Fire

Japan - 1
Katana

Alien - 4
Atrocitus, Starfire, Shade the Changing Man, Martian Manhunter

Unknown - 10
Girl in black, swampish thing, Deadman (dead), Tattooed woman, Unknown Lady 1, Unknown Lady 2, Wonder Girl, Unknown TT girl 1, Unknown TT girl 2, OMAC