It doesn't exist in appreciable amounts anywhere, that anyone knows of. Maybe you're confusing it with dark matter, which has only observed in distant galaxies (because it's only detectable -- to date -- by its gravitational effects).
Antimatter exists on earth. You're generating antimatter right now. One isotope of natural potassium (K-40) emits an antielectron in one in every 10^5 decays . A typical meatbag has enough K-40 for 4,400 decays per second  (i.e., 4.4 kBq), so you're spontaneously emitting, on average, about 3 antielectrons per minute from this path.