The Small Arms Survey, a research project run by a Swiss university, publishes a ranking of estimated civilian gun ownership by country.

While the survey is a trusted and widely used document, the numbers are based on averages that, in some cases — like Yemen and Switzerland — include big margins of error. With that in mind, there remains no doubt as to which country has the most guns in private hands.

1. The U.S. has 88.8 guns for every 100 residents.

Barack Obama said on Monday that his plan to tighten gun control is "well within" his authority and remains consistent with the Second Amendment, Americans' constitutional right to bear arms. 

USA-MILITIA North Florida Survival Group 2012

Members of a Florida survival group get ready for a training exercise near Old Town, Fla., in 2012. The group passionately supports the right of U.S. citizens to bear arms, according to its website. (Brian Blanco/Reuters)

2. Yemen has 54.8 guns per 100 residents.

The Saudi-led, U.S.-supported coalition in Yemen is enmeshed in a years-long fight against Iran-backed Houthi rebels, with al-Qaeda and ISIS exploiting the chaos to maintain a hold on the Arabian Peninsula. 

YEMEN-gun ownership 2014

Perhaps not surprisingly, war-ravaged Yemen is second on the list. This young Houthi boy was photographed in Sanaa in 2014. (Khaled Abdullah/Reuters)

Weapons belonging to the military are excluded from the Small Arms Survey, which is in part why Switzerland could rank anywhere from second to 16th, depending on whether the guns held by Swiss adults — many of whom are part of an armed civilian militia — count. In Yemen, access to accurate information poses a similar challenge to reporting.

3. Switzerland has 45.7 guns per 100 residents.

Switzerland is alone in Western Europe in its attitude toward gun ownership. Swiss men, all considered part of the militia after mandatory arms training, are permitted to keep their service rifles at home. In contrast to the Small Arms Survey figures, government numbers put gun ownership at about 25 for every 100 Swiss.

SWITZERLAND gun culture Ruetlischiessen shooting competition 2013

The Ruetlischiessen is an annual shooting competition dating from 1860. Until 2007, militia members (which included nearly all Swiss men) were required to keep a box of sealed, government-issued ammunition, along with their service rifles, in their homes. (Arnd Wiegmann/Reuters)

4. Finland is 45.3 for every 100 people.

Gun ownership in Finland is among the highest in the world, although crime rates remain among the world's lowest.

FINLAND high gun ownership rates

Hunter Reino Haapaa loads up at a shooting range in Kurikka, about 330 kilometres from Helsinki, in 2008. (Ints Kalnins/Reuters)

5. Serbia has 37.8 guns per 100 residents.

Bombed by U.S.-led NATO airstrikes in the 1999 war against forces loyal to Slobodan Milosevic, Serbia — which is steadily moving toward full ascension into the E.U. — re-entered the international arms market in the mid-2000s with deals to produce small-calibre guns for the U.S. arms firm Remington.

SERBIA gun ownership among worlds highest

A worker carries an assault rifle made at the Zastava Arms factory in the Serbian town of Kragujevac, some 137 kilometres from Belgrade, in 2013. (Marko Djurica/Reuters)

6. Cyprus has 36.4 guns for every 100 people.

The Mediterranean island nation of Cyprus, off the coasts of Turkey, Syria and Lebanon, has had a tumultuous history that includes a continuing, and at times violent, territorial dispute between Cypriots of Turkish and Greek ancestry.

Turkish and Greek CYPRIOT violence

A Turkish Cypriot man takes a load off next to a police officer in Nicosia, in the Turkish-administered northern part of the island, in 2010. (Murad Sezer/Reuters)

7. 35 guns for every 100 Saudis.

While firearms ownership and licensing are highly regulated in this country, Saudi Arabia is known to have a widespread black market trade in firearms.

Mideast Jordan Special Operations gun expo 2010

A Saudi visitor to the Special Operations Forces Exhibition and Conference, (SOFEX) held in Amman, Jordan, brandishes a pair of pistols at the expo in 2010. The military exhibition, billed as a networking event for global security, is an annual event. (Nader Daoud/AP)

8. Iraq has approximately 34.2 firearms for every 100 people...

But a total gun count is all but impossible after years of war following the 2003 invasion and 2011 pullout of U.S. forces. The Iraqi insurgency has continued as fighters from the Syrian civil war, as well as ISIS militants, have spilled into the country.

MIDEAST-CRISIS IRAQ forces backed by militia retake former Saddam fort from ISIS Oct 2015

Iraqi forces backed by militia fighters recaptured a mountain palace complex formerly owned by Saddam Hussein from ISIS fighters in October 2015, as government forces pushed ahead on a major offensive against the insurgents. (Thaier Al-Sudani/Reuters)

9. Uruguay has 31.8 guns per 100 people.

For a country with only 3.3 million people, firearms possession in Uruguay is unusually high with some 605,000 weapons registered with the government, according Nearly 89 per cent of Uruguay's registered gun owners are civilians, according to the defence ministry registry.

URUGUAY has a lot of guns for South America

Uruguayan soldiers stack confiscated guns in Montevideo during the launch of a program to decrease the number of civilian-owned guns circulating in the population in 2008. (Andres Stapff/Reuters)

10th and 11th place: Sweden and Norway have 31.6 and 31.3 firearms per 100 residents respectively.

SWEDEN has lots of guns hunter in Jan 2011

Swedish hunter Henrik Widlund takes part in the annual wolf hunt in Hasselforsreviret, in central Sweden, in 2011. That year, there was an allotted annual quota of 20 wolves for the area. (Anders Wiklund/Scanpix/Reuters)

Right behind France, which has 31.2 guns/100 people, Canada places 13th on the Small Arms Survey list with 30.8 firearms per 100 residents.

CANADA 13th on Small Arms Survey list of guns per capita

Competitors load their their guns (with blanks) during the Canadian Open Fast Draw Championships, held in Aldergrove, B.C., in 2013. (Andy Clark/Reuters)

With files from CBC