A couple things that correlate with this increase (whether or not they are causes):
- The rise of the internet (which really came into its own with graphic browsers, in the late 90s) and of new digital media in general, and the change in our electromagnetic environment with the growth of wifi and cellphone towers and so forth.
- Increased use of psychiatric medications, especially antidepressants.
https://www.psychiatry.org/news-room...se-on-the-rise
For that matter, "suicide prevention" has become more prominent in that time period, and yet, here we are with a rise in suicide.