It’s good to get a medical expert to explain. I’m not sure I fully understand, however, I have noticed in the past 5-10 years, all the sites have slowly been moving away from the above graph (I can’t even find the other 2 sites that used to have it).

So, the evidence seems to suggest you’re right. but, wouldn’t surprise me if its bad writing. I generally use the info off Alan Arnette’s site instead