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Only Spain and Serbia sang in their mother tongue, while France chose to perform in Corse.
Since the contest was created in 1956, winning songs have mostly been performed in English, with tunes sung in the language triumphing a total of 23 times.
French is also a popular contest language, with 14 victories. Dutch and Hebrew songs have won three times each.
As for individual countries, Ireland has won seven times, Luxembourg, France and the United Kingdom five times and Sweden and the Netherlands four times.
At first, participating countries were asked to sing in their national languages. But when the language rule was changed in 1999, each country has been free to choose which language it wants to sing in.
"We see a tendency in which some years, most contestants wish to sing in English, while sometimes, more singers perform in their own language," event supervisor Sietse Bakker told EurActiv.
Since the language rule changed in 1999, only one song performed in a language other than English has won the contest – that of Serbia's Marija Šerifović in 2007.
Press, artistic and composer awards
2011's Azeri duo were not the only winners of the contest.
Three other performances were also celebrated, with the annual Marcel Bezençon Awards presented in a ceremony backstage shortly before the final on Saturday evening (14 May).
These less well-known awards are presented in three categories – press, artistic and composer award – and were first handed out during the 2002 Eurovision contest in Tallinn.
This year's press award, given to the best entry as voted for by the accredited media and press during the contest, went to Paradise Oskar from Finland, who sang about ecological problems and saving the planet in 'Da Da Dum'.
The artistic award, given to the best artist as voted for by commentators, went to Jedward from Ireland who performed their catchy upbeat pop song Lipstick.
As for this year's composer award, the best and most original composition as voted on by the participating composers went to the French entry in Corse, Sognu, performed by Amaury Vassili.