The population of Ireland stood at 4,588,252 in 2011, an increase of 8.2% since 2006. , Ireland had the highest birth rate in the European Union (16 births per 1,000 of population). In 2014, 36.3% of births were to unmarried women. Annual population growth rates exceeded 2% during the 2002–2006 intercensal period, which was attributed to high rates of natural increase and immigration. This rate declined somewhat during the subsequent 2006–2011 intercensal period, with an average annual percentage change of 1.6%. The total fertility rate (TFR) in 2017 was estimated at 1.80 children born per woman, below the replacement rate of 2.1, it remains considerably below the high of 4.2 children born per woman in 1850. In 2018 the median age of the Irish population was 37.1 years.