could net the government up to £1.038 billion per year in fiscal revenue, however the long term implications of such a measure are uncertain. It has since been suggested that to deport all of the illegal immigrants from the UK might take 20 years and cost up to £12 billion. Former Mayor of London Boris Johnson commissioned a study into a possible amnesty for illegal immigrants, citing larger tax gains within the London area which is considered to be home to the majority of the country's population of such immigrants. In February 2008, the government introduced new £10,000 fines for employers found to be employing illegal immigrants where there is negligence on the part of the employer, with unlimited fines or jail sentences for employers acting knowingly. Women who are illegal immigrants and also domestic violence victims risk deportation and are deported if they complain about violence. Women get brought illegally into the UK by men intending to abuse them. Women are sometimes deterred from complaining about violence to them due to the risk of deportation, therefore perpetrators including rapists remain at large. Martha Spurrier of Liberty said, "It will leave people afraid to report crime, robbing them of protection under the law and creating impunity for criminals who target vulnerable people with unsettled immigration status. This is criminalising victims and letting criminals off the hook." Comparison of European Union countries According to Eurostat, 47.3 million people lived in the European Union in 2010 who were born outside their resident country. This corresponds to 9.4% of the total EU population. Of these, 31.4 million (63%) were born outside the EU and 16.0 million (32%) were born in another EU member state. The largest absolute numbers of people born outside the EU were in Germany (6.4 million), France (5.1 million), the United Kingdom (4.7 million), Spain (4.1 million), Italy (3.2 million), and the Netherlands (1.4 million). Citizenship laws Individuals wanting to apply for British citizenship have to demonstrate their commitment by learning English language, Welsh language or Gaelic language and by having an understanding of British history, culture and traditions. Any individual seeking to apply for naturalisation or indefinite leave to remain must pass the official Life in the UK test. Brexit See also British diaspora British nationality law Calais jungle Foreign-born population of the United Kingdom Immigrant benefits urban legend, a hoax regarding benefits comparison Immigration to Europe MigrationWatch UK