On that point, he's absolutely right: when it comes to gun homicide, the U.S. stands out from the rest of the world's wealthy nations. According to homicide data collected by the UN Office on Drugs and Crime, and compiled by The Guardian newspaper, the U.S.'s annual gun homicide rate of 2.97 fatalities per 100,000 people is triple the rate seen in most of the world's other wealthy nations, defined in this chart as countries belonging to the Organization for Economic Cooperation and Development. It excludes Latin American countries like Mexico that have traditionally had high murder rates, often due to political instability and the drug war.
"Our review of the academic literature found that a broad array of evidence indicates that gun availability is a risk factor for homicide, both in the United States and across high-income countries," according to the Harvard School of Public Health. "Case-control studies, ecological time-series and cross-sectional studies indicate that in homes, cities, states and regions in the US, where there are more guns, both men and women are at higher risk for homicide, particularly firearm homicide."