The debut of Stephen Colbert on “The Late Show” has been one of the most anticipated of the early fall season. But a scarcity of women on and behind the show illustrate just how little has changed when it comes to closing the gender gap on television.

Of the 19 writers for the show, two are women. Of Colbert’s eight guests in the first week, two — actresses Scarlett Johansson and Amy Schumer — were women.

Colbert’s show is hardly unique. And despite the successes of high-profile comedians such as Tina Fey as well as ABC’s show creator Shonda Rhimes, the reality is that women are still struggling to break into an industry largely dominated by men.

A new study released Tuesday illustrates the lack of progress for women in television.

Over the 2014-2015 television season, women made up 27 percent of the creators, directors writers and producers of prime time shows — a figure that hasn’t budged in five years, according to the report by the Center for the Study of Women in Television and Film at San Diego State University.

Women represented 42 percent of all speaking roles on broadcast television, a figure that has remained essentially flat for about a decade. It’s been particularly hard for women to find roles as they age compared to men who age, according to the study. The majority of female characters on broadcast and cable TV were in their 20s and 30s, while the majority of male characters were in their 30s or 40s, according to the annual report “Boxed In,” which has tracked female representation in television for the past 18 years.

“There is a perception gap between how people think women are faring in television, both on and behind the scenes, and their actual employment,” said Martha Lauzen, author of the report. “We are no longer experiencing the incremental growth we saw in the late 1990s and 2000s.”

Outside of prime time, the problem can be worse. Not a single host of a major late night show is female, for instance. CBS, which owns the “Late Show with Stephen Colbert,” did not respond to requests for comment. Over this week and next, 8 of the 20 guests for Colbert will be women, according to CBS’ Web site.

There is increasing pressure on the networks to address the under-representation of women on television. The ACLU asked state and federal agencies earlier this year to investigate whether movie studios and television networks have engaged in system discrimination of women for jobs as directors.

One solution, television analysts say, is to put more women in executive positions at television networks and in charge of shows. ABC’s Rhimes, who oversees “Scandal” and “How to Get Away with Murder,” feature minority female leading roles and diverse production, editing and writing staffs. Television creator Mary Brock Akil is also known for diverse casts in “Girlfriends,” “The Game,” and “Being Mary Jane.”

The San Diego study showed that programs with women in executive positions placed more female characters and hired more women to run the shows. On programs with at least one woman executive producer, 32 percent of writers were female compared, more than five times the share for programs with no female producers.

“Television and film are our most powerful cultural products and the fact that they are made overwhelmingly by men matters in the way women are portrayed,” said Melissa Goodman, an attorney with the ACLU of Southern California who filed the lawsuit against Hollywood and TV studios.

Correction: An earlier version of the story stated the ACLU filed a lawsuit against studios and networks. The ACLU asked for federal and state inquiries into hiring discrimination.