Most Important/Culturally significant country since the 40s.
Similar to us states this is in my opinion the most important country in each decade since the 40s.
40s - Germany: Responsible for WW2 and it's aftermath. Saw one of the awful events in human history that even in the 2020s have felt the effects.
50s - USA: Had a economic boom after WW2 and was the country that recovered the most. Created many inventions, Movies, Music, and movements that have caused effects we still have today.
60s - China: The great leap forward and China's famines made many Chinese people leave the country and immigrante to other countries. This made Chinese culture more spread out and Mao Zedong leadership has forever changed China and East asia's history
70s - UK: very difficult to pinpoint the country for the 70s but the UK music and movies have forever changed pop culture. From Queen to Pink Floyd, and also the James Bond movies The UK was culturally very significant and new music genres and subcultures.
80s - The Soviet Union: The country experienced decline and was breaking apart. The Cold war was at it's worse. The fall of the Berlin wall and many eastern European countries gaining independence changed everything. The breakup of the Soviet union have still created wars.
90s - USA: after the fall of the Soviet union America won the years long cold war. America saw massive improvements with a great economy, New music genres like Rap that started to become mainstream, and new inventions that further developed a new digital world.
2000s - Iraq: After 9/11 the Us and other countries invaded Iraq and Afghanistan. The war forever changed the middleast, caused a refugee crisis that we still have today, created new advancements in weapon technology and techniques. And created countless terrorist attacks and organizations.
2010s - South Korea/Japan: Both of these 2 countries had extreme cultural significance and technology that spread throughout the world. Kpop music became mainstream, Korean movies started to become mainstream. Korean companies like Samsung or Sony became huge. Japanese companies like Nintendo made games that sold millions and the Nintendo switch was huge. Anime became even more popular.
2020s - Isreal: Isreal saw a huge drop in popularity, benjamin Netanyahu became the world's new big enemy with even the the West dropping support. The Gaza war saw huge media and Internet attention. Benjamin netanyahu and isreal became memes with new ones like the Big Yahu. And antisemitism has started to become more spread sadly.