Here are some of the key statistics behind the second Eurovision semi-final, which is taking place tonight in Vienna.

:: A total of 17 countries are taking part in the second semi-final for this year’s Eurovision Song Contest. Only 10 will go through to Saturday’s final. Of the 17, seven are previous winners of the contest. Ireland has the best track record, having won seven times, most recently in 1996. Sweden has won it five times, Israel and Norway have each won it three times, Switzerland has won it twice, and Azerbaijan and Latvia have each won it once.

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How other countries fared in 2014 (PA Graphics)

:: In the first semi-final on Tuesday night, 10 countries made it through to the final: Armenia, Belgium, Greece, Estonia, Serbia, Hungary, Russia, Albania, Romania and Georgia.

:: In addition, seven countries will appear in the final without having competed in a semi-final. These are the host nation Austria, the guest nation Australia, and the five biggest contributors to the European Broadcasting Union: France, Germany, Italy, Spain and the United Kingdom.

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Past Eurovision winners (PA Graphics)

:: Out of all the countries taking part in tonight’s semi-final, Sweden fared best in last year’s contest, coming third and notching up 218 points. Norway also did particularly well, winning 88 points. In total 10 of the 17 countries in tonight’s semi-final made it to the 2014 final.

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A graphic showing how other countries did in the 2014 final (PA)

:: Viewers in all 17 countries appearing in the semi-final can take part, but their votes will count towards only 50% of the total scores. Professional juries will supply the other half. In addition, viewers and juries in Australia, Germany, Italy and the UK can also vote, meaning that a combination of 21 countries and 21 juries will determine the outcome of the semi-final.

:: Tonight’s competition will not be a particularly multilingual affair. Only two of the 17 entrants are singing in their native tongue. The other 15 are singing in English.

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Eurovision language spread explained (PA Graphics)

:: In all, 40 countries are participating in this year’s Eurovision Song Contest. This is not quite the highest number to date, however. The record remains 43 in 2011. Just seven countries took part in the very first Eurovision Song Contest in 1956.

:: Organisers of this year’s contest are promising a spectacle. The stage contains 300 LED strips, 450 LED floor modules and 1,288 illuminated slabs, and has been put together using 3,225 metres of tubing and 5,000 square metres of floor space. Centrepiece on the stage is a giant electronic eye 43 metres wide and 14 metres high.

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Eurovision growth (PA Graphics)

:: Around 800 people are involved in the production of the contest, while a further 800 volunteers have been recruited to help run the event. Some 1,500 journalists are expected to attend, and there is room for 11,000 spectators inside the venue, the Wiener Stadthalle.

:: A total of 27 countries will take part in the final on Saturday: the highest number in the contest’s history. A combined TV audience of around 200m is expected to watch on television.