Right around the 70s iirc. That's roughly when the modern progressive wing of the democratic party started to coalesce, and they've always had a big focus on it.
Though it's a little weird how much heat it generates given that it's only a "top 5" issue for about 6% of people. [0] If that few people people even bring it up on polls, I'd expect any attempts to create drama out of it to fall flat much more than they do.
[0] https://apnorc.org/wp-content/uploads/2022/01/AP-NORC-Decemb...
