A centenarian is a person who lives to or beyond the age of 100 years. Because life expectancies worldwide are less than 100, the term is invariably associated with longevity. A supercentenarian is a person who has lived to the age of 110 or more, something only achieved by about one in 1,000 centenarians. Even rarer is a person who has lived to age 115 – there are only 41 people in recorded history who have indisputably reached this age, of whom only Emma Morano, Violet Brown, Nabi Tajima, Chiyo Miyako and Ana María Vela Rubio are still living. In 2012, the United Nations estimated that there were 316,600 living centenarians worldwide. As life expectancy is increasing across the world, and the world population has also increased rapidly, the number of centenarians is expected to increase quickly in the future. According to the UK ONS, one-third of babies born in 2013 in the UK are expected to live to 100.
The United States currently has the greatest number of known centenarians of any nation with 53,364 according to the 2010 Census, or 17.3 per 100,000 people. In 2010, 82.8% of US centenarians were female.Japan has the second-largest number of centenarians, with an estimated 51,376 as of September 2012, and the highest proportion of centenarians at 34.85 per 100,000 people. Japan started recording its centenarians in 1963. The number of Japanese centenarians in that year was 153, but surpassed the 10,000 mark in 1998; 20,000 in 2003; and 40,000 in 2009. According to a 1998 United Nations demographic survey, Japan is expected to have 272,000 centenarians by 2050; other sources suggest that the number could be closer to 1 million. The incidence of centenarians in Japan was one per 3,522 people in 2008.
In Japan, the number of centenarians is highly skewed towards females. Japan in fiscal year 2016 had 57,525 female centenarians, while males were 8,167, a ratio of 7:1. The increase of centenarians was even more skewed at 11.6:1.