The evening sun illuminates Schoenbrunn palace in Vienna.
There are many countries that have restrictive immigration policies, while some have a welcoming policy.
Here we take a look at some countries that have given most citizenships between 2001 and 2010 in the world, according to an Organisation of Economic Co-operation and Development report.
A view of the downtown area in Los Angeles.
The United States
Naturalisations (2001-2010): 6.6 million
Foreign-born population of total (2010): 13 per cent
Global rank: 1
A view of Moscow's Kremlin, Ministry of Foreign Affairs and Moscow City Business District.
Russia
Naturalisations (2001-2010): 3.1 million
Foreign-born population of total (2010): N/A
Global rank: 2
People play volleyball on the front lawn of Parliament Hill in Ottawa.
Canada
Naturalisations (2001-2010): 1.7 million
Foreign-born population of total (2010): 20 per cent
Global rank: 3
Traffic on the road and the Thames passes the Houses of Parliament in London.
Britain
Naturalisations (2001-2010): 1.5 million
Foreign-born population of total (2010): 12 per cent
Global rank: 4
View of rooftops and the Montmartre's Sacre Coeur Basilica in Paris.
France
Naturalisations (2001-2010): 1.4 million
Foreign-born population of total (2010): 9 per cent
Global rank: 5
The skyline of Frankfurt with its bank towers is seen under clouds.
Naturalisations (2001-2010): 1.3 million
Foreign-born population of total (2010): 13 per cent
Global rank: 6
Rowers train at dawn on the Yarra River in Melbourne.
Australia
Naturalisations (2001-2010): 1 million
Foreign-born population of total (2010): 27 per cent
Global rank: 7
The lights system of the new Agbar Tower is tested in Barcelona.
Spain
Naturalisations (2001-2010): 0.6 million
Foreign-born population of total (2010): 15 per cent
Global rank: 8
People walk on Zurich's main shopping street Bahnhofstrasse.
Switzerland
Naturalisations (2001-2010): 0.4 million
Foreign-born population of total (2010): 27 per cent
Global rank: 9
View of the Turning Torso in the western harbour area of Malmo.
Sweden
Naturalisations (2001-2010): 0.2 million
Foreign-born population of total (2010): 15 per cent
Global rank: 10
Two women ride their bicycles on the Lindengracht in Amsterdam.
The Netherlands
Naturalisations (2001-2010): 0.2 million
Foreign-born population of total (2010): 11 per cent
Global rank: 11
Trams travel in downtown Milan.
Italy
Naturalisations (2001-2010): 0.2 million
Foreign-born population of total (2010): 8 per cent
Global rank: 12
People cross a street after rainfall in central Auckland.
New Zealand
Naturalisations (2001-2010): 0.1 million
Foreign-born population of total (2010): 23 per cent
Global rank: 13
Japan's Mt Fuji, covered with snow, is seen through Shinjuku skyscrapers in Tokyo.
Japan
Naturalisations (2001-2010): 0.1 million
Foreign-born population of total (2010): 2 per cent
Global rank: 14
A woman reads a book beside a bronze statue in front of Sejong Centre for the Performing Arts in central Seoul.
South Korea
Naturalisations (2001-2010): 0.1 million
Foreign-born population of total (2010): 2 per cent
Global rank: 15
