Median personal income in the US is ~$35,000, I think you must have looked at household. That $35,000 doesn't include people under 25. So the "7 billion" median would be even lower.
Still, that number doesn't seem accurate for the cut-off for the global 1%
2010 census has over 180,000,000 Americans over age 25. So assuming that there are people making more than $35,000 outside the US, this number still smells fishy...
Quickly looking at Wikipedia ( http://en.wikipedia.org/wiki/Household_income_in_the_United_... ) I see that the median household income is $50,233 and there are 116,011,000 households in the US. A quick googling shows there are about 316.1 million people in the US, yielding an average of 2.725 people per household. Dividing $50,233 drops our previous income figure down to $18,434.12 per person.