https://www.huffpost.com/entry/the-...0QXp6G41XAaOgUWV30QcI3-wZXWLBKndimvP922gi3LoS
"The real story is that when broken down, those 25.8 million trips overseas were taken by approximately just 13.3 million American residents. And that means that in total, the real number of Americans that actually traveled (took trips) overseas in 2009 for either business or leisure, was about 15.5 million --o r just five percent of our nation's 311 million residents!"
And yes, I realize this article is old but dont see any reason the %'s here would have changed significantly over this time. Also the point in the article is a good one that a large number of Americans traveling abroad are foriegn born citizens/permanent residents who are traveling to visit their birth country.