Gun ownership per capita in the US is more than three times that of Europe's highest country.
There were 39.1 firearms per 100 people in Montenegro, compared with 120 in the US, according to the Small Arms Survey (SAS)
Around 46% of all 857 million guns in civilian hands around the world belonged to people living in the United States in 2017, a survey has found.
The SAS found that gun ownership among civilians (84.6%) dwarfed state militaries (13.1%) and law enforcements’ (2.2%) stockpiles, and that number had grown by more than 200 million since 2006.
In total, it is thought that there are more than 1 billion firearms in possession across 230 countries and autonomous territories around the world.
The European Union's 513 million inhabitants owned a collective 79.8 million firearms in 2017. That figure grows to 93.2 million when including countries outside the EU, like Russia and Iceland.
The most guns were concentrated in Russia (17.6m), Germany (15.8m) and France (12.7m), while the rate of firearms owned per 100 people was highest in Montenegro (39.1), Serbia (39.1) and Cyprus (34). In comparison, there were around 120 firearms for every 100 US residents.
A 2013 report by the European Commission found that nine out of ten EU citizens had never owned a gun.
Among those who did own a firearm at the time of the survey, or who used to own one, over a third (35%) reported hunting as the reason for being armed; another 29% did so for professional reasons such as service in the police or the military; and a further 23% owned a firearm for use in sports such as target shooting.
Less common reasons given for possessing a firearm included personal protection (14%), other personal reasons (10%), and an interest in firearms as a collector (5%).
Between 2000 and 2012, the annual rate of all gun deaths per 100,000 population in the EU stood at 1.34 with 87,000 people losing their life, according to GunPolicy.org, an online resource for published evidence on armed violence, firearm law and gun control from the University of Sydney.
In the aftermath of deadly terror attacks in Paris and Brussels in 2015 and 2016, the EU tightened its Firearms Directive to ban converted semi-automatic firearms and standard capacity magazines of more than 21 rounds for pistols and 11 rounds for rifles. The European Parliament approved the measure in a March 2017 vote with 491 in favour and 178 against.
Aaron Karp, the SAS survey author told reporters last year that "the biggest force pushing up gun ownership around the world is civilian ownership in the United States. Ordinary American people buy approximately 14 million new and imported guns every year."
"Why are they buying them? That’s another debate. Above all, they are buying them probably because they can. The American market is extraordinarily permissive," he added.
The United States is one of the few countries where the right to bear arms is protected by the state constitution. The Second Amendment of the United States Constitution states: "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
According to the US-based Pew Research Centre, protection tops the list of reasons given for owning a firearm with 67% of gun owners saying so. Hunting (38%), sport shooting (30%) and gun collecting (13%) came next.
Most (44%) of the Pew survey's respondents stated that they personally know someone who has been shot, either accidentally or intentionally and a majority (57%) say gun laws should be more strict.
According to Brady, a US gun violence prevention group, 310 people are shot in the United States every day. Among those, 100 are killed and another 61 die from suicide.
Mass shootings are also incredibly common in the US with 340 recorded in 2018, according to Gun Violence Archive, an online resource compiling data from law enforcement. In 2017 and 2016, the group recorded 346 and 382 such events.
Still, respondents of the Pew survey were divided over whether stricter gun ownership rules would lead to fewer mass shootings with 47% believing that to be the case and 46% saying it would make no difference.
Former President Barack Obama announced plans for stricter gun laws in an emotional 2016 speech referencing the Sandy Hook shooting, which saw the mass shooting of children and teachers in 2012.
His attempts to pass stricter rules were criticised by the powerful National Rifle Association lobby group and were ultimately unsuccessful.
In February 2017, President Donald Trump signed a bill into law rolling back an Obama-era regulation that made it harder for people with mental illnesses to purchase a gun.