I don't understand, who cares what percentage the US is to the world population? How about a comparison of people who can actually afford tickets? 20% of the population in east Europe and Central Asia live on less then $2 a day, 50% of sub Sahara Africa lives on less then $1 a day, 25% of North Africa/middle east live on less then $2 a day, 85% of south east Asia lives on less then $2 a day and 50% of east Asia/pacific lives on less then $2 a day. The homeless guy on the corner of I45 and FM1960 here in Houston has a better chance of getting a ticket then these people in the other regions.