A new study has found what seems to be obvious: higher levels of gun ownership mean more deaths from gun fire.
Researchers in the United States looked at gun ownership, crime rate, firearms-related deaths and depression in 27 developed countries.
They found the correlation between gun ownership and gun deaths was massive.
While gun ownership is rare in Japan and the United Kingdom, it's high in both the US and South Africa.
Can you guess the difference in the gun-related death rate?
In Japan it's 0.06 per 100,000 people. In South Africa, it's 9.4 per 100,000 people. In the UK, the rate is 0.25 per 100,000, while in the US it is 10.2.
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"This argues against the notion of more guns translating into less crime," said study author Sripal Bangalore, a cardiologist at New York University School of Medicine.
"You could say that if there is a lot of crime in a society people will feel insecure, so they buy guns and there's a vicious cycle," he said.
The researchers found a much weaker correlation between mental illness and gun deaths.
The countries surveyed were Australia, Austria, Belgium, Canada, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Israel, Italy, Japan, Luxembourg, Malta, the Netherlands, New Zealand, Norway, Portugal, South Africa, Spain, Sweden, Switzerland, Turkey, the UK and the US.
The study was based on data from the World Health Organization.
It was published online in the American Journal of Medicine.