Since 1950 the longevity of persons reaching their 80th birthday was much higher for someone in the United States than it was in other developed countries. The United States population averaged another 6.5 years of life after age 80. Beginning in 1990 the United States' longevity gains have leveled off at an average of 8.5 years after the age of 80. There is no known explanation for this leveling off. Many have tried to explain it, but no true evidence is available. Other developed countries have begun to catch up with the United States average. Japan has surpassed the United States with a longevity gain of approximately 8.75 years after the age of 80.
Source: UC Berkely 1997