Universal’s feel-good musical ‘Mamma Mia’ has totaled an eye-popping $307 million outside the United States, dwarfing its $139 million domestic take. And with back-to-back first-place finishes, it has kept overall foreign business decent at a time when moviegoing often lags.

Combined with its sensational performance at the US box office, “The Dark Knight” has totaled $919 million worldwide and become only the 10th pic to go past $900 million by that measure. It’s the second-best foreign performer this year, trailing only “Indiana Jones and the Kingdom of the Crystal Skull” with $466 million.

With disruption from two major sporting events and fewer slam-dunk franchise pics, the overseas numbers weren’t expected to duplicate 2007’s stunning performance. But a variety of films that weren’t sure bets — notably “Mamma Mia!,” “Sex and the City,” “What Happens in Vegas” and “Kung Fu Panda” — managed to dazzle outside the U.S.

There were twists and turns that no one predicted. Who would have bet that “Indiana Jones and the Kingdom of the Crystal Skull” would not have the summer’s biggest opening, or that “The Dark Knight” and “Iron Man” would outgross it? Bottom line: Success at the box office can be determined by a confluence of mysterious factors.

In recent press interviews, ‘Indiana Jones’ producer George Lucas has said that the three principals–himself, director Steven Spielberg and star Harrison Ford–would all have to agree on the idea before production on a fifth film could move forward.