The number of terrorism-related deaths fell for a second year in 2016, even though more countries in the West were affected as tactics shifted to lone-wolf attacks.

According to the fifth annual Global Terrorism Index, by the Institute for Economics and Peace, deaths from terrorism fell 13% to 25,673 last year, and were 22% lower than the 2014 peak.

Terrorism is defined in the report as “the threatened or actual use of illegal force and violence by a non‐state actor to attain a political, economic, religious, or social goal through fear, coercion, or intimidation.”

The United States suffered more deaths related to extremist attacks in 2016 than in any year since the 9/11 attacks in New York, according to the report. Attacks caused the deaths of 64 people, the report said, which was a 240-percent increase in deaths from terrorism in the U.S. from 2014, when only 19 people died in extremist attacks.

Nigeria saw the greatest drop in number of deaths (80%) as regions in the north were retaken from militant Islamist group Boko Harem. Other countries to experience significant declines included Afghanistan, Pakistan, and Iraq.

More countries experienced at least one terrorism-related death in 2016 than in any other year since 2001, with 77 countries affected – 11 more than in 2015.

According to the report, 94% of all terrorism-related deaths happened in the Middle East and North Africa, sub-Saharan Africa, and South Asia.

Four of the five countries most affected by terrorism – Syria, Pakistan, Afghanistan, and Nigeria – recorded an improvement, according to the report. Nigeria saw an 80% reduction in terrorism-related deaths, as Boko Haram has been hit hard by the Multinational Joint Task Force.