The oldest of the International Science Olympiads, the IMO has since been held annually, except in 1980.
That year, the competition initially planned to be held in Mongolia was cancelled due to the Soviet invasion of Afghanistan.
Seven countries entered – Bulgaria, Czechoslovakia, East Germany, Hungary, Poland, Romania and the Soviet Union – with the hosts finishing as the top-ranked nation.
[7][8]) There have been other disqualifications of contestants due to cheating, but such cases are not officially made public.
[9] In January 2011, Google gave €1 million to the IMO organization to help cover the costs of the events from 2011 to 2015.