63 percent of iPhones were sold outside the US in Q3

[AT&T] activated 5.2 million iPhones in the wake of the iPhone 4 launch, or about a 62.5 percent leap over an already record spring

via AT&T blows past records, activates 5.2m iPhones in summer | Electronista.

This means 63% of iPhones sold outside the US last quarter.  This is down from about 70% earlier this year. As it was a launch quarter and distribution was much more constrained outside the US, the lower figure is not surprising.

It’s still important to note however that sales outside the US are far larger than in the US but penetration and share is far less.