We have plenty. I am basing this conclusion on radar trackings showing UFOs with speeds far superior to any aircraft known on our planet.  There are observations from pilots and military officers.  Former astronaut Edgar Mitchell, the sixth man to walk on the Moon, believes that the UFOs are extraterrestrial. Carl Sagan and others have estimated that life and civilizations are abundant in the universe.  There is considerable opposite opinion that life, especially complex life is rare. See this book:   Rare Earth: Why Complex Life is Uncommon in the Universe  by Peter D. Ward  (Author), Donald Brownlee  (Author) A reviewer on Amazon explains the rare earth thesis:

Renowned paleontologist Ward (Univ. of Washington), who has authored numerous books and articles, and Brownlee, a noted astronomer who has also researched extraterrestrial materials, combine their interests, research, and collaborative thoughts to present a startling new hypothesis: bacterial life forms may be in many galaxies, but complex life forms, like those that have evolved on Earth, are rare in the universe. Ward and Brownlee attribute Earth’s evolutionary achievements to the following critical factors: our optimal distance from the sun, the positive effects of the moon’s gravity on our climate, plate tectonics and continental drift, the right types of metals and elements, ample liquid water, maintenance of the correct amount of internal heat to keep surface temperatures within a habitable range, and a gaseous planet the size of Jupiter to shield Earth from catastrophic meteoric bombardment. Arguing that complex life is a rare event in the universe, this compelling book magnifies the significance and tragedy of species extinction.

This 25 minute presentation explains the case:

Why we might be alone in the Universe

https://www.youtube.com/watch?v=PqEmYU8Y_rI

Our visiting ETs have come from huge distances using anti-gravity technology and wormholes.