Image copyright Getty Images Image caption Elizabeth Banks and Sam Taylor-Wood directed hit films Pitch Perfect 2 and Fifty Shades of Grey

Just 9% of Hollywood's highest grossing films last year were directed by women, the same level as 1998.

A report by the Centre for the Study of Women in Television and Film looked into the jobs of people working on the top 250 films in Hollywood.

It found that women made up 19% of all directors, writers, producers, executive producers, editors, and cinematographers.

That is up 2% on last year but is the same level as 2001.

Dr Martha Lauzen, the study's author, said it was "unrealistic" to expect attitudes to women directors would change over night but "nothing in this data suggests that change is on the horizon."

Lauzen said the success of high profile directors such as Pitch Perfect's Elizabeth Banks and 50 Shades of Grey's Sam Taylor-Wood hid the wider picture.

"Every time a film directed by a woman does well that's positive. But there can be a negative aspect," she said.

"Heads of studios will use a few high profile cases to say we're doing our part or to say that there is a problem of under-employment, just not at their studio. It's a double-edged sword."

In May, the American Civil Liberties Union in Southern California sent letters asking federal and state civil rights agencies to investigate the systemic failure to hire women directors at all levels of the film and television industry.

In October, it was reported that the Equal Employment Opportunity Commission in the US had begun contacting female directors to investigate gender discrimination in Hollywood.

The gender gap in Hollywood pay also took centre stage last year after Jennifer Lawrence wrote an essay about unequal pay.

Opening doors

Lauzen's report also showed films with women in the directing chair opened the door to women in other roles behind the scenes.

Films that had at least one female director (including assistant directors), employed more women as writers, editors, and cinematographers than films with exclusively male directors.

On films with at least one woman director, women made up 53% of writers compared to 10% if the directors were exclusively men.

In a similar comparison, women comprised 32% of editors, compared to 19% if the directors were male.

Historically, the report showed that while the percentage of directors has remained the same since 1998, the percentages of executive producers, producers, editors, and cinematographers have increased.

However, in the same time the percentage of women writers has declined from 13% to 11%.

The report showed that in 2015 women fared best in Hollywood as producers - making up 26% of posts. They made up 22% of editors, 11% of writers and 6% of cinematographers.