Worldwide terrorism is at an all-time high, and violence cost the global economy $14.3 trillion last year, with a $2.5 trillion impact in the United States alone.

These new figures from the latest Global Peace Index, a report on conflict and security, indicate that world peace has been deteriorating for the past decade, largely driven by terrorism and conflicts in the Middle East and Northern Africa.

The study says the decline interrupts long-term improvements the world had been making since the end of World War II.

According to the report, the annual number of terrorism incidents has almost tripled since 2011.

Deaths from terrorism have risen more than 900% since 2007 in the 35 countries that are members of the Organization for Economic Cooperation and Development. Of those members, 23 nations experienced terrorism related deaths over the past year.

Those countries include Denmark, Sweden, France and Turkey.

A snapshot of the state of global peace



US effect

The United States has dropped 11 places in the study's ranking, falling to the bottom spot among developed nations. Experts say the U.S. has experienced a significant rise of internal conflict due to political polarization. In addition, the homicide rate has gone up in several major American cities, and measures of the impact of terrorism were affected by several attacks including a shooting in an Orlando, Florida nightclub in which 49 people died.

Steve Killelea, founder of the Institute for Economics and Peace, which produces the yearly study, said tensions in the United States have an international effect.

"The increased political polarity in the U.S. is being experienced across the developed world," he said. "This is driven by underlying conditions of increasing inequality, rising perceptions of corruption, a lack of acceptance of rights of others, and falling press freedoms. These factors underpin the U.S. decline in peace and signal potential future increases in instability and violence."

The economic impact of violence in the United States equals $2.5 trillion, or 9 percent of the nation's gross national product - nearly $5,000 per person.

Largest changes in scores from 2016



Terrorism and internal conflict

Among all the nations ranked, Syria was the least peaceful, due both to internal conflict and to terrorism.

Across the Middle East, "battle deaths from conflict are at a 25-year high, and the number of refugees and displaced people are at a level not seen in 60 years," the Institute said.

Worldwide, deaths from terrorism increased by 80 percent from last year. The intensity of terrorism also increased; 11 countries last year lost more than 500 people to terrorist acts, when only five nations experienced that kind of death toll the year before.

The majority of terrorist activity was concentrated in five countries: Iraq, Nigeria, Afghanistan, Pakistan and Syria.

The Global Peace Index annually measures 163 countries and territories for domestic and internal conflict, safety and security, and each nation's degree of militarization.