These charts show why we keep getting more 'Pirates of the Caribbean' and 'Transformers' films

International ticket sales are the driving factor behind why studios keep making "Pirates of the Caribbean" and "Transformers" movies.

If you've looked at the movie listings this weekend, and asked yourself "Why is Disney making another 'Pirates of the Caribbean film?" you're not alone.

The fifth installment "Dead Men Tell No Tales" opens Friday in the U.S. With each new addition to the Pirates' franchise, the reviews have gotten worse and the U.S. audiences have shrunk. But overseas, fans are still enamored with Johnny Depp's swashbuckling portrayal of Captain Jack Sparrow.

International markets have driven the majority of box office revenue for the "Pirates" franchise since the first film was released in 2003. At the box office "Curse of the Black Pearl" saw a pretty even split between U.S. and international ticket sales, but with each additional release, that gap has widened.

By the fourth film, "On Stranger Tides," more than 75 percent of box office revenue was earned overseas, a whopping $804.8 million.

For comparison, the film garnered $241 million in the U.S., less than the opening weekend gross of "Star Wars: The Force Awakens."

"U.S. audiences have been subjected to so many sequels over the decades that it is hard to maintain the excitement," Paul Dergarabedian, senior media analyst for comScore, told CNBC.

Despite the lackluster performances in the United States, two of the "Pirates" films have garnered more than $1 billion in total global ticket sales and one fell just shy of the mark with $962 million.

Dergarabedian said that international audiences, particularly in China, India and South America, still embrace these films because they grew up on big American blockbusters and enjoy the action-packed adventures.

"Action is the international language and that's what audiences really respond to," he said.

"The Pirates of the Caribbean" franchise isn't the only one that gets an international boost. The "Transformers" films have also been met by lackluster reviews and U.S. audience fatigue.

The fourth "Transformers" film, "Age of Extinction," which was released in 2014, garnered more than $858.6 million in international tickets. Domestically, its ticket sales for the full run of the film were about $245 million.

Dergarabedian attributed the film's international success not only to the action sequences, but the cast of Mark Wahlberg, an action movie star, and the fact that much of the film took place in a city in China. He said that international audiences like to see films set on a global stage.

"If you look at the numbers, international has to be at the forefront," Dergarabedian said. "Appealing to global audiences is the driving force."

That's why this summer a fifth "Transformers" film, "The Last Knight," will hit theaters.

While several cast members of the "Pirates" franchise have hinted that there could be more films in the future, the studio does not currently have any plans for a sixth installment.

"Transformers," on the other hand, is slated to release at least four more films after "The Last Knight," one of which will be a standalone "Bumblebee" movie set for release in 2018.

Disclosure: NBC Universal, the parent of CNBC, has a licensing agreement with the "Transformers" franchise.