Allsång på Skansen (Sing-along at Skansen) is a Swedish show held at Skansen, Stockholm, every summer on Tuesdays between 8pm and 9pm. The audience is encouraged to sing along with musical guest stars to well-known Swedish and international songs. The show started in 1935 on a small scale; about 50 people in the audience. Today, about 10,000–25,500 people come to each performance. Since 3 August 1979 the show has been broadcast by Sveriges Television. Initially the show had about 300,000 viewers. When Lasse Berghagen took over as host, the ratings increased to about 2 million viewers.
https://en.wikipedia.org/wiki/Alls%C3%A5ng_p%C3%A5_Skansen