FYI: The numbers reported above were self reported bone pressed measurements. Here are the measurement instructions for the survey from the same website:
With a rigid ruler handy, standing straight up or kneeling, get a full erection. Lay the ruler along the top of your penis, and press the end of the ruler firmly against your body (where the pubic hair is). Hold your penis against the ruler with your hand, straighten out as much as possible any curvature that may exist, and try to hold your penis so that it’s sticking straight out from your body. Then determine the ruler reading at the very end of your penis and round off to the nearest quarter-inch. If your ruler has centimeters only, calculate the number of corresponding inches (1 inch = 2.54 cm) and write it down.