A new report says nearly 18,000 people were killed in terrorist attacks in 2013, some 60 percent more than the year before.
The Global Terrorism Index, published on November 18 by the London-based Institute for Economics and Peace, said there were 10,000 terrorist attacks in 2013.
Four militant groups -- the Islamic State (IS) group, Boko Haram, Al-Qaeda, and the Taliban -- were responsible for most of the attacks and 66 percent of the fatalities, the study said.
It said Iraq was the country most affected by terrorism, with 2,492 attacks that killed more than 6,300 people in 2013.
Most of the attacks were blamed on Islamic State militants.
According to the report, more than 80 percent of the deaths from terrorism occurred in Iraq, Afghanistan, Pakistan, Nigeria, and Syria.