Out of eight billion people, only around three quarters of a million are centenarians according to research by the United Nations, a rarity of about one in eleven thousand. By 2100, the UN projects twenty-five million centenarians out of ten billion people, a rarity of about one in four hundred (this assumes no longevity therapies are developed by then). We should thus expect only around fifteen thousand supercentenarians by then.
Based on the survival rate of centenarians to 110, the Gerontology Research Group estimates there are only, at most, 450 living supercentenarians worldwide; meaning there's one supercentenarian for every eighteen million people.
Also,
the odds are far worse for men than for women. Only fifteen percent of centenarians are male, and that may drop to ten percent for supercentenarians. (Even after correcting for males' increased exposure to violence, danger, and bad diets, women still have a significant physiological advantage.)
Only
seventy-five people (including just three men) have verifiably lived to 115, and Jeanne Calment remains the
only person verified to have reached 120.