Terrorism deaths fell last year thanks to a weakening of the Islamic State group in Iraq and Boko Haram in Nigeria, but both groups expanded their geographic reach, a new index revealed Wednesday.

Some 29,376 people died from terrorism in 2015, down 3,389 on the previous year and the first fall since 2010, according to the Global Terrorism Index published by the Institute for Economics and Peace.

The Global Terrorism Index is a study that accounts for the direct and indirect impact of terrorism in 162 countries in terms of its effect on lives lost, injuries, property damages and the psychological aftereffects of terrorism.

It aggregates data on terrorism today, the Global Terrorism Database collated by the National Consortium for the study of terrorism and responses to terrorism into a composite score.