Via the Guardian: 

Latest statistics show the proliferation of privately owned guns is on the rise, with wealthy countries outstripping developing and war-torn countries.

In a detailed report, weapons watchdog the Small Arms Survey has researched the numbers of guns across 230 countries. 

Examining the ownership of revolvers and self-loading pistols, rifles, carbines, assault rifles and sub- and light machine guns, held by civilian, military and law-enforcement groups, their latest report shows there are now estimated to be more than 1bn firearms in the world – an increase of 17% over the past 10 years.

The majority of the arms, 85% (857m), are estimated to be held by civilians (including individuals, private security firms, non-state armed groups and gangs); while law enforcement agencies own 2% (23m) and military stockpiles account for 13% (133m)...

The United States has just 4% of the world population, but the survey estimates that civilians in the US possess almost 40% of the world’s firearms – 393m weapons – equivalent to 121 firearms for every 100 residents. Americans topped the polls in 2007, owning 270m weapons, which translated into 90 weapons for every 100 residents.

Read more here.