in 1815, below the replacement rate of 2.1, but higher than the 2001 record low of 1.63. In 2011, 47.3 per cent of births in the UK were to unmarried women. The Office for National Statistics published a bulletin in 2015 showing that, out of the UK population aged 16 and over, 1.7 per cent identify as gay, lesbian, or bisexual (2.0 per cent of males and 1.5 per cent of females); 4.5 per cent of respondents responded with "other", "I don't know", or did not respond. The number of transgender people in the UK was estimated to be between 65,000 and 300,000 by research between 2001 and 2008. Ethnic groups Historically, indigenous British people were thought to be descended from the various ethnic groups that settled there before the 12th century: the Celts, Romans, Anglo-Saxons, Norse and the Normans. Welsh people could be the oldest ethnic group in the UK. A 2006 genetic study shows that more than 50 per cent of England's gene pool contains Germanic Y chromosomes. Another 2005 genetic analysis indicates that "about 75 per cent of the traceable ancestors of the modern British population had arrived in the British isles by about 6,200 years ago, at the start of the British Neolithic or Stone Age", and that the British broadly share a common ancestry with the Basque people. The UK has a history of non-white immigration with Liverpool having the oldest Black population in the country dating back to at least the 1730s during the period of the African slave trade. During this period it is estimated the Afro-Caribbean population of Great Britain was 10,000 to 15,000 which later declined due to the abolition of slavery. The UK also has the oldest Chinese community in Europe, dating to the arrival of Chinese seamen in the 19th century. In 1950 there were probably fewer than 20,000 non-white residents in Britain, almost all born overseas. In 1951 there were an estimated 94,500 people living in Britain who had been born in South Asia, China, Africa and the Caribbean, just under 0.2 per cent of the UK population. By 1961 this number had more than quadrupled to 384,000, just over 0.7 per cent of the United Kingdom population. Since 1948 substantial immigration from Africa, the Caribbean and South Asia has been a legacy of ties forged by the British Empire. Migration from new EU member states in Central