This only covers stellar black holes. (Note that this black hole is believed to be a stellar black hole.) Those statistics could change quickly if you add to it a currently unknown number of primordial black holes that arose around the Big Bang.
If those primordial black holes are mostly on their own, and are both numerous and small, they make a potential candidate for dark matter. They could also be potentially small enough to be evaporating in our current era. This has been suggested as a potential source of a very high energy neutrino that was found in February. See https://www.livescience.com/space/black-holes/evidence-for-s....
(Note that this is just a single observation. We are a very long way from being able to obtain strong experimental evidence for such speculative theories.)
If those primordial black holes are mostly on their own, and are both numerous and small, they make a potential candidate for dark matter. They could also be potentially small enough to be evaporating in our current era. This has been suggested as a potential source of a very high energy neutrino that was found in February. See https://www.livescience.com/space/black-holes/evidence-for-s....
(Note that this is just a single observation. We are a very long way from being able to obtain strong experimental evidence for such speculative theories.)