As TinyPrincess said this data you are referring to has been discredited, I have written about it before on this forum. It's complete pseudoscience, in many cases taken from self-reported data.
If you want penis sizes from different countries go on pubmed and look up penis size studies
Home - PMC - NCBI
none support major racial differences. Your find most fall into the range of 5 and 5.5 inch.
The idea that congo men on average have 7.1 inches is a bizarre fantasy. Jonny Sins a well known American pornstar is that penis size and its huge in real life. Do you really think on average men are walking around with pornstar cocks in congo? The world average penis length is not above 5.5. The high 6 or 7 range is a myth.
Link to a scientific study demonstrating your claims in a science journal, you will find that you cannot. You are parroting discredited nonsense, its been long debunked here at LPSG.