Reflecting the explosive growth of the international box office, the rate at which studios are hitting overseas milestones is quickening, with 20th Century Fox the latest major, after Disney and Warner Bros., to reach the $1 billion overseas threshold — in a little more than five months.

According to Fox, the studio’s international division crossed the B.O. milestone for a 12th year, nine of which are consecutive. In 1999, Fox didn’t reach $1 billion internationally until December, however.

With Disney and Warners already having crossed $1 billion last month, 2012 marks only a few years during which at least three studios reached $1 billion at the overseas box office in such a short time frame. It took the same three studios only slightly less time to hit that milestone in 2010, though Fox led the charge after just 30 days then, thanks to “Avatar.”

So far this year, Fox earned most of its overseas coin from “Titanic” in 3D, which grossed $286 million, of which more than half came from China. The studio’s “Alvin and the Chipmunks” 2011 threepeat earned $135 million this year; pic’s total tally reached $211 million. “Prometheus,” meanwhile, helped push Fox over the threshold this past weekend, grossing $35 million from 15 markets.

Of the studios that have yet to cross $1 billion internationally, Sony and Universal likely will do so by the end of the month, as both to date stand at nearly $800 million. Sony has “Men in Black 3,” which reached $400 million worldwide, while U’s “Snow White and the Huntsman” debuted last weekend in 45 territories with $39 million.

Paramount rounds out the majors with $646 million internationally to date.

Though hitting $1 billion still is an impressive achievement, the bar for studios is now much higher.

Last year, Par became the first studio to gross more than $3 billion internationally in a single year, while three other studios — Warners, Disney and Fox — reached the $2 billion mark. That same trio stands to do so again this year, while Par is suffering from a lack of product this year that will make it unlikely to even come close to repeating its 2011 milestone; studio may struggle to earn half that.

Sony should hit $2 billion internationally, thanks to “The Amazing Spider-Man” and “Skyfall,” and potentially U, with “The Bourne Legacy.”