With the unexpected success of Twenty Two, which topped the global documentary box-office charts in 2017, Chinese producers who make such films are on a roll, says a report recently released by Beijing Normal University.

The report shows that 16 documentaries were screened in Chinese theaters in 2017, grossing 269 million yuan ($ 43 million), a year-on-year revenue growth of 237 percent.

Twenty Two, a film about sexual slavery during World War II, made a record 170 million yuan, making it the first documentary in Chinese cinematic history to surpass the 100-million-yuan mark.

The other documentaries that did well include Sino-UK production Earth: One Amazing Day and Return to the Wolves, a 98-minute film about a Chinese painter working to return an orphan wolf back to the wild, grossing 47.78 million yuan and 33 million yuan, respectively, to take the second and third slots.

In 2017, China invested nearly 4 billion yuan in total to produce movie and television documentaries, which grossed more than 6 billion yuan.

The two figures are an increase of 14 and 15 percent, respectively, year on year.

"In China, there is sufficient market space for high-quality documentary films," says Zhang Tongdao, who headed the team that wrote the report.

Zhang, who is also the director of the Documentary Center at Beijing Normal University, says that Chinese viewers' diverse tastes in film also bodes well for the documentary sector.

For Guo Ke, the 38-year-old director of Twenty Two, the crowd-funding campaign to raise money for the film shows that a quality documentary can work with Chinese audiences, who were seen earlier to prefer only action-studded films or slapstick comedies .

The crew of Twenty Two contacted more than 32,000 people through WeChat message groups across 50 cities, and their enthusiasm helped boost the documentary's popularity online.

Guo says that his next film will also be a documentary, as "the power of truth in documentaries is overwhelming".

Another industry highlight last year was the global outreach of Chinese documentaries.

In 2017, Chinese documentary makers continued to team up with global partners to reinvent the style and substance of documentary storytelling.

China: Time of Xi, a three-episode television series on China's policies and their impact over the past five years, is a case in point.

The series, co-produced by China Intercontinental Communication Center, Discovery Networks Asia-Pacific and Meridian Line Films, was aired across around 30 countries and regions in October.

On CGTN's YouTube channel, the documentary received more than 274,000 hits and 770 comments.

The television series features President Xi Jinping's undertakings and philosophies, such as targeted poverty alleviation, supply-side structural reform and the Belt and Road Initiative.

Speaking about the series, Vikram Channa, the vice-president of Production and Development at Discovery Networks Asia-Pacific, says: "The challenge (when it comes to such a documentary) is how to make policy into a story."

Calling the series "a choreography of multiple opinions", Channa, who is also the producer of China: Time of Xi, says the hope is that "it (the series) can communicate hard policies in an intimate and personal way".

Liu Yinglun contributed to the story.