SAN FRANCISCO (CBS SF) — A recently published book on reported UFOs sightings found California had the most visual encounters with unidentified objects in the United States, including hundreds of reported sightings in the Bay Area.

The book analyzed more than 120,000 reports of UFOs and found Californians believed they’d come in contact with extraterrestrial life more often than anyone else in the country.

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“We found that UFOs were sighted in every county in the United States. Every county had at least one sighting sometime in the past 15 years,” explained “UFO Sightings Desk Reference” co-author Cheryl Costa.

Costa spoke to KPIX 5 via Skype from her home in upstate New York.

Using data from the Mutual UFO Network or MUFON and the National UFO Reporting Center, she said Californians reported seeing nearly 16,000 UFOs between 2001 and 2015.

“We think a great deal of it has to do with California’s weather,” said Costa.

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Costa explained that California’s mild weather allows people to be outdoors during much of the year and thus in position to spot possible UFOs.

According to Costa, Santa Clara County topped the list in Northern California with 569 reported sightings. Alameda County was second with 518, while San Francisco trailed with 327.

It should be noted that these reports are anecdotal haven’t been investigated. Despite what the true believers will tell you, there is still no irrefutable proof of the existence of extraterrestrial life.

But for those who believe we’re not alone in the universe, the book is a first step is converting science fiction into established fact.

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“Most people were very sincere about what they reported; about what they think they saw, said Costa. “They weren’t jerking us around. But we understand the only proof some people are going to accept is a space ship cracked up in the mall parking lot.”