Is this "knowledge"? The very first sentence in the introduction of this study "virtually" debunks that notion:
"The true prevalence of doping among athletes competing at the highest level remains virtually unknown ..."
And yet somehow you claim to know, and that I know, and that you know I know, something that your own reference says "remains virtually unknown"?
This alone proves my point. Should we bother to read any further? It doesn't get any better.
Reading on we can find significant expressed limitations with the WC blood data: "one should note that the method used to determine prevalence estimates may produce a notable upward bias" and "altitude exposure prior to the competitions as a confounding factor ... data about prior altitude exposure were missing for Daegu and only partially recorded in Moscow ..."
Anonymous surveys are no better. First and foremost, the question is whether anonymity ensures survey compliance. It is most troubling that the survey researchers recommended discarding 30% of their own data based on survey response time, in order to remove a large 12 percentage point bias (e.g. from automatic "yes" responders), without any guarantees that they removed all of the bias in the remaining 70% of the data. We cannot be sure the survey result reflects true doping prevelance, unbiased by survey respondant apathy.
Rather than calling it "knowledge", here's what your reference says: "these results shall first underline the large variability and heterogeneity in the determination of doping prevalence with a questionable significance."
Furthermore:
The question I raised here, in this thread about Kenyans, is about Kenyans who intentionally dope. In the 2011 analysis, only 47 of the 1808 athletes were Kenyan. In the 2013 analysis, only 49 of the 1875 athletes were Kenyan. WC Kenyans represented about 2.6% of the total WC athlete population.
From the other side, most of the Kenyans being busted today, among the "hundreds, if not thousands", in the Kenyan "pyramid" of "top-class" athletes, are not WC athletes.
Is the historical data collected from 2011 and 2013 even relevant today? This predates the IAAF-Russian scandal, and the creation of the AIU, and doesn't reflect any deterrent from the WADA investigations, raised public awareness, and increased testing.