Only about a tenth of participants in the March for Our Lives rally in Washington D.C. over the weekend were actually minors, according to a sociology professor's analysis.

University of Maryland professor Dana R. Fisher has been surveying rallies and protests in the nation's capital since Donald Trump's inauguration in preparation for an upcoming book on the "Resistance" to the president. In a Washington Post analysis published Wednesday, she detailed how she randomly sampled 256 attendees of the gun-control rally.

"Contrary to what's been reported in many media accounts, the D.C. March for Our Lives crowd was not primarily made up of teenagers," Fisher wrote. "Only about 10 percent of the participants were under 18."

"The average age of the adults in the crowd was just under 49 years old, which is older than participants at the other marches I've surveyed but similar to the age of the average participant at the Million Moms March in 2000, which was also about gun control," she continued.

Fisher found that the march did manage to draw in a higher-than-average percentage of first-time protesters, about 27 percent. But of those first-timers, only 12 percent said they were motivated by the issue of gun control, with over half saying they were motivated by Trump or "peace" in general.