I don't disagree that they're probably a major contributor, but the first statin came on the market in 1987 (Mevacor, by Merck), and the line is well on the dow

I don't disagree that they're probably a major contributor, but the first statin came on the market in 1987 (Mevacor, by Merck), and the line is well on the down-slope by that point. In fact, more than half its drop (for US data) comes before that point.