70% of Palme d’Or winners have come from just 7 countries: USA, Italy, France, UK, Japan, Sweden and Denmark. 58% from the first four alone. Counting the other 8 countries who have won the Palme more than once, 88% of the winners of the top prize at Cannes hail from just 15 nations.
Dominance by the United States, Italy, France and the UK was strongest from 1950-1980, when those four countries won the Palme d’Or 29 times in a span of 3 decades. (That was 76% of the time, since the Palme is occasionally awarded to 2 films in the same year).
Half of the Palme d’Or winners the United States has ever won happened in the ’70s. From 1970-1980, films from the USA won the Palme d’Or seven times: MASH, Scarecrow, The Conversation, Taxi Driver, Apocalypse Now and All That Jazz.
(In the early years, prior to 1955, the top prize was called the Grand Prix du Festival International du Film — so those those winners are counted on this chart.)