They come from all parts of the world to the USA the “land of plenty!”
In looking over the International Boxing Organizations top 100 list of contenders plus world champions of the WBO, WBC, WBA, IBF & IBO I found the following:
WORLD BELT HOLDERS CONTENDERS
Hvy Wt USA 1 of 5 24% USA
Cr Wt USA 0 16% USA
Lt Hvy USA 1 of 5 19% USA
Sup Mid USA 1 of 5 20% USA
Mid Wt USA 0 21% USA
Sup Welt USA 4 of 5 23% USA
Welt USA 3 of 5 30% USA
Sup Lt USA 3 of 5 20% USA
Lt Wt USA 2 of 5 16% USA
Sup Fly USA 1 of 5 15% USA
Fea Wt USA 1 of 5 10% USA
Sup Ban USA 1 of 5 7% USA
Ban Wt 0 6% USA
Sup Fly 0 8% USA
Fly Wt USA 1 of 5 1% USA
Lt Fly 0 1% USA
Min Wt 0 0% USA