Background
I have recently stumbled across a paper which analyzed the correlation between the IMO medal and future success in the mathematical area. So, inspired by annual predictions of IOI rankings based on CF ratings, I don't know what to do with my time decided to take a more "serious" approach.
Method
I collected the data from the last $$$7$$$ editions of IOI in order to create the graph of $$$f(x)$$$ is the maximal rating of the participant of rank $$$x$$$. For the last $$$6$$$ editions, I relied almost solely on the IOI statistics website. The $$$2012$$$ edition, however, is missing a lot of information and I collected the CF handles either from snarknews or by finding the handle on search engines.
I put the participants in the same order they were arranged in the scoreboard, so if there are multiple people on the same position, they would be assigned consecutive ranks. In case there was an unofficial participant, I assigned the mean of the ranks between which this participant was situated.
If there were participants with no competitions, I assigned the rating $$$1500$$$. This should not have big influence on the graph because there were very few such participants.
IOI 2012
IOI 2013
IOI 2014
IOI 2015
IOI 2016
IOI 2017
IOI 2018