Image copyright Getty Images Image caption Lady Bird director Greta Gerwig (left) and Wonder Woman's Patty Jenkins enjoyed success in 2017

Only 11% of the highest-grossing movies in the US last year were directed by women, researchers have found.

The study, conducted by San Diego State University, looked at the top 250 films at the US box office in 2017.

Overall, it found that women comprised just 18% of directors, writers, producers, executive producers, editors and cinematographers.

That figure is barely higher than the 17% who held such roles 20 years ago, in 1998.

The most successful film with a female director in 2017 was Patty Jenkins' Wonder Woman - the ninth top-grossing film of the year.

Proportion of top 250 films with female directors

2017 - 11%

2016 - 7%

2015 - 9%

2014 - 7%

2013 - 6%

The proportion of female directors rose by four percentage points in 2017 - up from 7% the previous year. It was the first time the figure had reached double figures since 2000, when it was also 11%.

The study also found that 83% of the top 250 films films had no female writers.

The issue of gender equality among directors has been a big talking point, and was addressed by actress Natalie Portman at Sunday night's Golden Globes.

Introducing the best director category, she said: "And here are the all-male nominees."

The nominations for next month's Bafta film awards were announced earlier this week - and, again, the best director category was exclusively male.

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