It’s also not a perfect asymptote thanks to Bolt… It fell by .02 from '99-'06, then .03 in '07, then comes Bolt to lower it by .2 by '09. If it wasn’t an asymptote before, I’d say it sure is one now although Bolt did show that freaks can do naughty things to trend lines. Even so he probably just accelerated the rise toward the ceiling.