Airline accidents declined dramatically in 2015, making it the safest of the past five years.

There were 136 deaths from four accidental airline crashes last year, according to a report from the International Air Transport Association. That's less than a quarter of the death toll from 2014, when 641 people died in airline accidents.

"In terms of the number of fatal accidents, it was an extraordinarily safe year," said Tony Tyler, CEO of the Montreal-based air industry group.

The IATA said that all of last year's fatalities involved turboprop aircraft, not jets. The annual average over the last five years is 17.6 fatal accidents and 504 fatalities.

Since this is a tally of accidents, it does not include two major plane crashes that were caused deliberately. The crash of Germanwings 9525 in the French Alps that killed 150 people was blamed on pilot suicide. The crash of Metrojet 9268 in Egypt that killed 224 was blamed on terrorism.

Most aircraft accidents are non-fatal. The IATA said there 68 total accidents last year, compared to 77 the year before.