homes. Water supply and sanitation Access to improved water supply and sanitation in the UK is universal. It is estimated that 96.7 per cent of households are connected to the sewer network. According to the Environment Agency, total water abstraction for public water supply in the UK was 16,406 megalitres per day in 2007. In England and Wales water and sewerage services are provided by 10 private regional water and sewerage companies and 13 mostly smaller private "water only" companies. In Scotland, water and sewerage services are provided by a single public company, Scottish Water. In Northern Ireland water and sewerage services are also provided by a single public entity, Northern Ireland Water. Demographics A census is taken simultaneously in all parts of the UK every 10 years. In the 2011 census the total population of the United Kingdom was 63,181,775. It is the fourth-largest in Europe (after Russia, Germany and France), the fifth-largest in the Commonwealth and the 22nd-largest in the world. In mid-2014 and mid-2015 net long-term international migration contributed more to population growth. In mid-2012 and mid-2013 natural change contributed the most to population growth. Between 2001 and 2011 the population increased by an average annual rate of approximately 0.7 per cent. This compares to 0.3 per cent per year in the period 1991 to 2001 and 0.2 per cent in the decade 1981 to 1991. The 2011 census also showed that, over the previous 100 years, the proportion of the population aged 0–14 fell from 31 per cent to 18 per cent, and the proportion of people aged 65 and over rose from 5 to 16 per cent. In 2018 the median age of the UK population was 41.7 years. England's population in 2011 was 53 million, representing some 84 per cent of the UK total. It is one of the most densely populated countries in the world, with 420 people resident per square kilometre in mid-2015, with a particular concentration in London and the south-east. The 2011 census put Scotland's population at 5.3 million, Wales at 3.06 million and Northern Ireland at 1.81 million. In 2017 the average total fertility rate (TFR) across the UK was 1.74 children born per woman. While a rising birth rate is contributing to population growth, it remains considerably below the baby boom peak of 2.95 children per woman in 1964, or the high of 6.02 children born per woman