Having born in the 70's Ive seen a big transition. I can only go on personally what I've seen, so other people might have different ideas.
70's - 80's merged into one big decade for me lol
90s - started about 1991 with dance music, more issues being addressed and being discussed be it sexism, racism, LGBTQ+. It was a start of shift of attitudes. Technology was improving and getting smaller.
2000's this started in 1999. Y2K compliant, people getting excited for the millennium celebrations, making plans for a new century.
2010- from flip phones to iphones. from there on in what ever changes there was its been a gradual change. Maybe brexit year divided the nation ?and then the start of 'cancel' culture.