China's box office grew by 48 percent this year through December compared with 2014 totals — the biggest jump ever — fueled by successful local-language film releases, a trend that should continue in the coming year, experts said.

Box-office totals broke 40 billion yuan ($6.3 billion) last week, with domestic films accounting for 59 percent of the earnings, and foreign films making up the rest.

Because December is a "blackout" period for imported films — no new foreign releases will be allowed during this month — foreign films' percentage at the box office will shrink more, experts said.

"That percentage might even drop," said Jonathan Papish, who tracks the Chinese box office for China Film Insider. "It will drop. I don't know how much, but it looks like the imported percentage will be under 40 percent, and that will be perhaps the lowest in history in the Chinese box office. In 2008, it was 39 percent, and it can even dip lower than that this year. That's not great for Hollywood."

He said that this year was "pretty disappointing for American films", despite record-breaking grosses for films like Furious 7 and Spectre and movies that are part of franchises like Avengers: Age of Ultron and Jurassic World.

"Hollywood would say that it's the scheduling. Hollywood studios don't really have any say on the release date, and it's all up to SARFT," Papish said, referring to the State Administration Radio, Film, and Television in China.

"They kind of packed in the Hollywood releases, especially the fall and winter, and didn't really allow the films to break out as much as they could, because they were really going against each other, cannibalizing their box-office revenues," he said.

Another reason is that major growth at the Chinese box office is coming more and more from third- and fourth-tier cities, and they tend to prefer more local-language films like Lost in Hong Kong and Monster Hunt, two of the largest-grossing Chinese-language films at the box office this year.

Lost in Hong Kong outgrossed Avengers: Age of Ultron, bringing in $253.6 million compared with $240.1 million, respectively. Monster Hunt, a 3-D fantasy adventure film, brought in $381 million.

"I think it was a strong year, a reflection of fantastic growth happening in the market," said Daniel Loria, senior overseas analyst at BoxOffice.com.