Furthermore, less than half of the 62 known wild African lion populations have over 100 lions. However, the vulnerability of different lion populations cannot be assessed simply through their size. Almost all of the remaining African lion range is within countries that rank in the 25% poorest countries in the world. This leaves the remaining African lions vulnerable to the pressures felt by many of the poorest countries and communities in the world. The researchers estimate that the costs for protecting all the remaining African lions may be as high as US$3 billion annually.