Things were definitely different to today, but I think the factors you listed are not enough to explain the massive decline in that graph.
Things like economic insecurity, cost of housing, increasing isolation / changes in living circumstances, and medication are all likely to be significant factors in my opinion.
You think 1990 where a time of full consent and awareness about other sensitivities? Oh boy.
Things were definitely different to today, but I think the factors you listed are not enough to explain the massive decline in that graph.
Things like economic insecurity, cost of housing, increasing isolation / changes in living circumstances, and medication are all likely to be significant factors in my opinion.