I found this illustration of terrorist incidents since 2000 (page 14 of the report) to be particularly interesting, worthy of reflection:
The enormous increase in deaths from terrorist actions since 2011 is clear, and seems to be correlated with the Syrian civil war. The growth of deaths related to terrorism after the US invasion of Iraq is also notable, as is the decrease after the troop “surge” in 2007.
Prior to the recent attacks, the situations in Iraq and Nigeria are very worrisome.
Many thanks to the Institute for Economics and Peace for this important document, which helps us understand the facts and, perhaps, some aspects of the causes.