The last time I saw a study on this, there was way less variation between country averages. This also seems to very much confirm existing social biases, which I'd be wary of.
Yep, was going to mention a study from a few years ago that threw out most of this data as junk since they found many were counting stretched flaccid as "erect".
This data isn't really worth much without any info on variation.
But really, the societal obsession with penis size is deeply unhealthy for everyone, but especially men. We should strive to value all bodies for their inherent beauty and stop comparing them. There isn't any better or worse. Please stop reproducing those norms. Same goes for all other body related norms. They go hand in hand with sexism, racism, ableism, queerfobia and all kinds of discrimination and objectification.