in France form the largest ethnic group after French of European origin. According to Michèle Tribalat, a researcher at INED, there were 3.5 million people of Maghrebi origin (with at least one grandparent from Algeria, Morocco or Tunisia) living in France in 2005 corresponding to 5.8% of the total French metropolitan population (60.7 million in 2005). Maghrebis have settled mainly in the industrial regions in France, especially in the Paris region. Many famous French people like Edith Piaf, Isabelle Adjani, Arnaud Montebourg, Alain Bashung, Dany Boon, Zinedine Zidane and Karim Benzema have Maghrebi ancestry. Below is a table of population of Maghrebi origin in France, numbers are in thousands: In 2005, the percentage of young people under 18 of Maghrebi origin (at least one immigrant parent) were about 7% in Metropolitan France, 12% in Greater Paris, 13% in Lyon, 21% in Perpignan, 22% in French département of Seine-Saint-Denis, 37% in 18th arrondissement of Paris and 40% in several arrondissements of Marseilles. 16% of newborns in France between 2006 and 2008 have at least one Maghrebi grandparent. Their number increased in the following years. According to other sources between 5 and 6 million people of Maghrebi origin live in France corresponding to about 7-9% of the total French metropolitan population. As of 2011, there were 4.5 million Algerians in France of which 42% were women. Illegal immigration Illegal immigration to France has developed as the country's immigration policy has become more rigid. In 2006, The French Ministry of the Interior estimated clandestine immigrants ("sans-papiers ") in France numbered anywhere between 200,000 and 400,000, also expecting between 80,000 and 100,000 people to enter the country illegally each year. In 2011, 28,000 illegal immigrants were expelled from France. The French government set a goal of 35,000 for 2012. The French government threatened to withdraw from the Schengen accord in 2009, 2011 and 2012. As of 2016, many undocumented immigrants tried to jump the fences at Calais and board a train or truck heading for Britain. The Home Office has agents working alongside French police and immigration agents to prevent unauthorized people from entering the British border zone. Citizenship Children born in France to foreign parents are automatically granted French citizenship upon reaching the age of 18. People born abroad and living in France can acquire French citizenship if they satisfy certain conditions. In 2009 the number of naturalised persons was 135,000, mainly from