Reply to classicsnoot: in your referenced article the estimated US population is 317 million, and the world population is 7134 million. 317/7134=0.444 so the US population is then 4.4% of the world population.
thanks to you and @alpeper, i appreciate you reserving judgement i used to be embarrassed of my poor maths skills, but now i do not have the time for silly feel.