Data from US-based NUFORC (National UFO Reporting Center) shows UFO reports have been in decline since 2014.

Alex Griffioen of the Netherlands' UFO Disclosure Office said fewer UFO sightings may be due to people attributing them to drones.

But Head of the National UFO Reporting Center Peter Davenport suggested reports could be being intercepted too.

Reports of UFO sightings has been in massive decline for the past few years. According to data from US-based NUFORC (National UFO Reporting Center) the slump started in 2014, after years of increased sightings.

Since the 1990s, the overall number of UFO observations steadily increased, reaching a peak of 8,670 reports in 2014. After that, it all went quickly downhill, as this infographic from Statista.com shows.

Alex Griffioen of the Netherlands' UFO Disclosure Office said that the quantity of reports in the Netherlands hadn't seen the same drop. Statista / National UFO Reporting Centre

NUFORC didn't have a website in the 1990s, so it makes sense that there were fewer reports received at that time, but since 2014, the number of observations at NUFORC fell to 5,500 in 2016. This figure fell again to 4,500 in 2017, and — while 2018 isn't over yet — it now stands at 1,329 reports .

Although this is still considerably more than any figure recorded in the 90s, it must be stressed that that period was pre-internet, so reports weren't yet being received via the website. This only makes the decline after 2014 all the more striking.

It's true that such incidents are more commonplace than in the 90s, but why the number has fallen so sharply after 2014 remains a mystery. Have extraterrestrial beings lost interest in us? Are we not looking carefully enough? Or is there a better explanation?

It's largely a case of guesswork but there are possible theories

"The significant decrease in the number of reports has baffled everyone investigating within the UFO field," founder and director of NUFORC Peter Davenport said to Business Insider. He's previously discussed the decline with members of the Mutual UFO Network. "They see the same trend and they're all confused by it."

According to him, there are many possible explanations. "It could just be that there are fewer and fewer incidents, but it's also possible that reports to UFO organisations are being intercepted electronically. Who would do something like that is a mystery, but if it's happening, my first suspicion would be government organisations. It's quite risky for a government to do that, but you can't rule it out, I think."

Reports of UFOs peak in 2012 due to the end of Mayan calendar

According to Alex Griffioen, one of the founders of the UFO Disclosure Office in the Netherlands, it's difficult to draw a conclusion from the NUFORC figures.

"That's just one source. A decrease in the number of reports doesn't actually equate to a drop in the number of UFO sightings. It may also mean the NUFORC website has become more difficult to find or perhaps less useful," suggested Griffioen.

The quantity of reports in the Netherlands doesn't seem to have dropped in the same way, according to Griffioen, who says the number of observations at the UFO Disclosure Office in the Netherlands peaked in 2012.

"In 2012, of course, we had the upcoming apocalypse as the end of the Mayan calendar approached," laughed Griffioen.

"The peak in our statistics around 2012 is also possibly due to certain sections of the public — who were anticipating some form of alien apocalypse — being overly alert to extraterrestrial encounters," he said.

Drones could be a likely culprit for the decrease

If the number of observations has decreased worldwide, there could be two main reasons for this according to Griffioen: "Drones are becoming cheaper and more popular, and are taking on stranger and stranger shapes every day. This applies to both military UAVs (Unmanned Aerial Vehicles), professional drones for video as well as for recreational drones."

"We hear and read that they can do more and more, so people now respond to seeing strange moving lights with: 'it'll be a drone'."

Laws around commercial drones in the US have relaxed

In 2015, the Federal Aviation Administration (FAA) began allowing companies to send drones into the air, provided they comply with certain guidelines. Amazon, for example, started delivering via drones and CNN began using UAVs to film from the air. Until 2015, this was prohibited, unless you'd received a special exemption to carry out such flights.

In December 2015, the FAA also stipulated that drones weighing over 250 grams had to be registered with the organisation, in anticipation of the holidays when it was estimated that 700,000 drones would be purchased.

According to the Consumer Technology Association, more than 2.4 million drones were sold in the US alone in 2016, more than double the figure for 2015.

Fighter jets can sometimes look strange in the sky

The chance of encountering a drone has grown considerably, which could account for people identifying what previously would have been considered a UFO as a drone.

But in fact, there's a whole plethora of things that could be mistaken for extraterrestrial objects in the night sky, ranging from fighter jets and natural phenomena like lenticular clouds, to dirt on camera lenses and unusually-shaped kites.

Still sure you've definitely seen a UFO? For extraterrestrial visits wherever you are, you can always contact NUFORC or MUFON to log a report.