A centenarian is a person who lives to or beyond the age of 100 years. Because life expectancies everywhere 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 39 people in recorded history who have indisputably reached this age, of whom only Susannah Mushatt Jones, Emma Morano-Martinuzzi, Violet Brown and Nabi Tajima 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 rise fast in the future. According to the UK ONS, one-third of babies born in 2013 in the UK are expected to live to 100.