I think it probably depends on the sort of content you write and a whole host of other factors including length and whether you write in a niche to a selected audience or not. I'm a generalist

I try and keep my read ratios above 40% and for the most part I sit at the 40% - 60% mark. Once I go above seven minutes there's a fairly steep drop to between 30% and 40%. Anything below 30% and I usually scrap the story as not fit for purpose - it's either a) too long b) the title is too clickbaity and the article doesn't deliver because of the structure or c) I'm writing absolute horse dung.

The exception to that rule is when I have a shit tonne of traffic to the piece coming from off Medium. That means I've accidentally written something google is interested in - and that'll push my stats to low 20s every time. The piece stays, and I enjoy having 12K views and $0.20 to show for it :o)