Unfortunately, no one seems to have ever done a poll on UFO's to determine the actual incidence of sightings among the population of American and other countries. Most polls already set the stage for replies by tying UFO's to extraterrestrial life. Most often, the simple questions that should be asked are not (Have you personally ever seen an object in the sky that you still feel you cannot identify? Was it a point of light, or like a meteor, or a discernible object? If an object, what shape and color was it? How long did you see it? Did it move in a straight path, or did it maneuver? etc etc).
The press and pollsters seem to have never figured out that UFO's are not necessarily tied to extraterrestrial life. The infamous SciFi-Channel-sponsored Roper Poll of 2002 was almost entirely composed of X-files-type questions - whether people believed extraterrestrial life existed, whether a government cover-up of UFO's existed, and so on.
Polls are often dramatically self-inconsistent In a 1997 poll reported by USA Today, 66% believed a UFO crashed at Roswell, but only 45% believed in intelligent life on other planets, and only 26% believed space aliens had visited earth. The Roper Poll breathlessly proclaimed that 40% of Americans had shown signs of alien abduction, but this meant only that they reported things like waking up paralyzed (a common conventionally-understood phenomena) or had seen a ghost. Compare this with 2% (with an error of plus/minus 3%!) who reported they had encounters with extraterrestrial beings. This poll was done randomly by phone, with all the problems such (or any poll) presents. Presumably only those with no interest in the topic hung up.
The only long-term, randomly-sampled information on how many UFO's are seen were in a series of Gallup opinion polls administered from 1966 to 1990. Unfortunately, these polls used slightly different terminology and in some years ruined the lead-in by preceding questions linking UFO's with extraterrestrial life. And note the way the question is commonly phrased - "Have you ever seen anything you thought was a UFO?" Presumably those who reply yes to this include some of those who saw something they thought could be a UFO at first - but on further observation or thought concluded it was something identifiable. But, for what they're worth (typical error plus/minus 3%):
|Type||Ever Seen||Reported||Ratio Seen:Reported|
So, it seems that at most only 1 in 450 UFO sightings results in a report. The comparison of the ratio of the different types of sighting in the derived seen versus reported data indicates that the reports do indeed represent a pretty good cross-section of experiences. The ratio is pretty consistent from type to type, given the meager data, except for the CE1's. But given the ambiguity of the Roper Poll question, some self-reported Close Encounters would probably normally be categorized as DD/NL reports.
It is interesting that over the 60-year history of UFO's, there is no obvious trend in the poll numbers for numbers seen. What this can only mean is that the phenomena, whether mental or actual, occurs at a constant rate and rare rate, so that the same percentage of people believe they have seen something in 1966 as 2007, even though over half of the people alive in 1966 and responding to the poll have since passed on, replaced by people who were not taking polls or even born in 1966. That means the chance of a particular person seeing a UFO in their adult lifetime amounts to around 1 in 12 - the chance per year, about 1 in 600, and the chance on any particular day 1 in 219,000. Of course these chances are all 100 times higher in rural areas then in cities.
To put it another day, on any particular evening there are around 1000 sightings of UFO's around the USA, including 100 close encounters with objects (CE1 or 2), 80 encounters with humanoids (CE3), and 15 abductions. In the United States there are now living around 1 million people who believe they have seen saucer occupants, and over 150,000 who believe they have been abducted.
This might seem like overwhelming evidence. But consider also that three times more people (23%) say they have actually seen a ghost or believe they have been in one's presence (AP poll of October 2007). On the other hand, only 27% have been in a tornado and 32% in a hurricane (Gallup poll). But we all believe in the reality of tornadoes and hurricanes, but not necessarily ghosts or UFO's.