There's not too many of those years though -- where a single film like Titanic so dominantly overwhelms the year.
Jaws 1975
Star Wars 1977
E.T. 1982
Batman 1989
Jurassic Park - 1993 (despite Schindler's List, the dinos seemed to be everywhere that year)
Titanic 1997
Avatar - whenever it was, 2009?
There might be another two to three I'm missing depending how far back you want to go, but that's about it.
I would add TDK in 2008. That was huge too. I remember it on the news and even on sports talk shows on ESPN talking about the film. Avengers 2012 is another rbig one.
If we go far enough there's The Wizard of Oz, Casablanca, Psycho, the Graduate etc.
The thing is, I can remember films being culturally impactful in a particular year, yet today, those films might not be as popular, but they did own those years regardless of their status today.
Some examples, Jerry Maguire in 1996. That thing was annoyingly popular. That year also had Independence Day, which had the biggest shot of the year, the white house blowing up. Mission Impossible was popular too. Scream, maybe the most famous opening to a horror film, and a film that was parodied to death. I don't know that any of those films are popular today tho.
1999 was all about American Beauty, the critical darling that nobody remembers today, but there was also The Blair Witch Project, Fight Club, The Sixth Sense, The Matrix, TPM, Austin Powers, The Green Mile, The Mummy. Very difficult to pick just one at the time, but today I choose, Matrix, which had a legitimate impact in the 2000's action genre.
I think 2019 was a weak year overall, but there's no denying that there's something about Joker dancing on the steps that stands out as one of if not the most memorable image of the year.