To many, 2016's Ghostbusters offered a viable model for big-budget Hollywood tentpoles starring women. To others, it was proof that Hollywood shouldn’t strive for more equitable gender representation. Those heated arguments were only the latest iteration of an ongoing debate about diversity in Hollywood—a more inclusive film industry has been a long time coming. And it isn't coming quickly enough, according to Inequality in 800 Popular Films, a new study from the Media, Diversity, & Social Change Initiative at USC’s Annenberg School for Communication and Journalism.

The study, which examines representation in the 100 top-grossing domestic films annually, from 2007-2015, evaluates more than 35,000 characters for gender, race/ethnicity, and LGBT status. The initiative has released annual reports since 2007; in the 2015 study, it also assessed whether these films portray character disability. And the findings are disheartening. “When you think of different identity groups, we’re seeing a broad-brush erasure,” says co-author Stacy Smith.

Among the top 100 films of 2015, 49 films did not include a speaking Asian or Asian-American character; 17 featured no African-American characters. LGBT-identified characters represented less than 1 percent of speaking roles, and those with disabilities clocked in at only 2.4 percent. And despite an increase in the percentage of female leads since 2014, the percentage of female speaking characters hasn’t meaningfully changed in the past eight years.

The conversation is at a fever pitch, but we wanted to provide analysis away from the chatter about inclusion. These efforts could create extraordinary change—they just have to catch fire. Stacy Smith, co-author of USC's study

The lack of onscreen diversity, the study finds, is due at least partially to a parallel lack of diversity behind the camera. In 2015, the top-grossing 100 films were the work of 107 directors, eight of whom were women; over the study's eight-year span, only 36 of 886 directors have been female (that's 4.1 percent). If people from under-represented groups have a chance to direct and tell stories, the study posits, they’ll choose a more diverse range of people throughout the process.

There are significant data points that may help turn that tide: Ava DuVernay’s and Ryan Coogler's films; Paul Feig’s Ghostbusters; Ryan Murphy’s commitment to have 50 percent of director positions on his shows filled by women, people of color, and LGBT individuals. But beyond these voices for change, the industry is noticeably silent. “Until we see multinational, muscle-bound production companies deciding to target inclusion goals and be transparent in those goals, we won’t see change around these biases that have been entrenched for decades,” says Smith. For movies to start to look more like real America, the entire development and production process has to become more inclusive.

In the study, Smith and her co-authors go beyond data analysis to suggest a course of action. If producers committed to adding five female speaking characters in each movie, and repeated the process for three years, films would reach gender parity by 2018. Smith sees this not only as opening doors for women, but changing the industry to include people from underrepresented groups more broadly. “You could add them from a diverse range of backgrounds and perspectives, and build a pipeline of work for those actors,” says Smith. As another possible method, the paper suggests equity riders: If top-earning stars included a clause in their contracts requiring casting reflective of real-world demographics, it would call for small steps towards diverse representation.

Smith admits that suggestions buried in the conclusion of a study don't often spark industry change, but she maintains the importance of offering possible solutions instead of just diagnosing the problem. “The conversation is at a fever pitch, but we wanted to provide analysis away from the chatter about inclusion,” says Smith. “These efforts could create extraordinary change—they just have to catch fire.”