The United States has 90 guns for every 100 citizens, making it the most heavily armed society in the world, a report released on Tuesday said.
U.S. citizens own 270 million of the world's 875 million known firearms, according to the Small Arms Survey 2007 by the Geneva-based Graduate Institute of International Studies.
About 4.5 million of the 8 million new guns manufactured worldwide each year are purchased in the United States, it said.
