How many performers were allowed to be on the stage at the same time in the Eurovision Song Contest in 2011?

Explanation

In 1956 there were no limitations on the number of performers. Between 1957 and 1960, only solo or duo acts were allowed to perform. From 1963 onwards, you could bring a choir consisting of a maximum of three people. Since 1973, the rule of maximum 6 people on the stage has been in place.