Of course many don't have the choice - from the UK, you either have to have employment in a role that can't be undertaken by a US citizen or a very large bank balance (OK, the rules may have changed over the years, so please be kind if things have changes and this is now inaccurate!!!). I know 2 people who would love to have stayed after having part of their education in the US, but couldn't. And of course there are a number of US students who study in locations around the world who return to the US after their studies.

I love statistics