The FBI designated the recent shootings in San Bernardino, Calif., a terrorist attack, but President Barack Obama used his Oval Office address on the events to include a reference about the need for more gun control.

Just four days after the attacks that left 14 dead, Obama said: “We also need to make it harder for people to buy powerful assault weapons like the ones that were used in San Bernardino.”

Although Obama didn’t specifically call to renew the old assault weapons ban — in effect in the U.S. from 1994 to 2004 — Obama’s namechecking of gun control reignited conversations about the effectiveness of the previous law. Using data from a Mother Jones investigation on mass shootings in the United States, InsideGov explored the ban’s impact on gun violence in America.

The data shows that of the 73 mass shootings that have occurred since 1982, 16 involved assault weapons. As the visualization below illustrates, while the ban was in effect, assailants used assault weapons in four shootings. Since the ban expired, nine such shootings involved assault weapons, including the one in San Bernardino.

Studies examining the impact of the ban found the law didn’t prevent violence or decrease crime rates. A task force within the Centers for Disease Control and Prevention researched the effectiveness of strategies for preventing violence, looking at gun laws as a possible means to avert violence. The study, released in October 2003, “found insufficient evidence to determine the effectiveness of any of the firearms laws or combinations of laws reviewed on violent outcomes.”

The 1994 provision, signed into law by then President Bill Clinton, called out 18 specific firearms, large-capacity magazines that hold more than 10 rounds of ammunition and certain military features that could be added onto guns. It banned the future manufacture of the specific guns and the magazines, but didn’t pertain to anything manufactured before the law went into effect in 1994.

That meant the ban couldn’t touch the 1.5 million assault weapons and 24 million large-capacity magazines already in circulation before the law was signed. A June 2004 University of Pennsylvania report about the effectiveness of the ban found that the prevalence of these grandfathered-in items meant it was “premature” to assess the law’s impact on gun crime.

Without question, violence continued throughout the years the assault weapons ban was in effect. But a different metric provides a new perspective of the ban’s impact.

The visualization shows how many people have died in mass shootings since 1982, breaking out totals by year. The average number of fatalities dipped during the 10 years the ban was in effect. From 1982 to 1993, about nine people, on average, died during each shooting. From 1994 to 2004, that average went down to approximately seven fatalities. When the ban expired in 2004, the average bounced back to about nine deaths per attack.

With the exception of 1999, in general, the years during the assault weapons ban saw fewer fatalities as a result of mass shootings. In 1999, five mass shootings claimed a total of 44 lives: 15 people died at Columbine High School in Littleton, Colo.; nine people died at two day-trading firms in Atlanta; eight people died at Wedgwood Baptist Church in Fort Worth, Texas; seven people died at a Xerox building in Honolulu; and five people died at the Radisson Bay Harbor Inn in Tampa, Fla.

A revamp of the nation’s firearms laws seems unlikely, especially since we are embarking on a presidential election year and politicians often prefer to sidestep volatile topics like gun legislation on the campaign trail. While an assault weapons ban wouldn’t necessarily eliminate mass shootings or gun violence, the data does suggest it might lower the number of fatalities during such attacks.

More: The States With the Most Gun Violence

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