Research by a University of Illinois professor has revealed that contrary to what many people think, mass murders are not on the rise in the United States.

According to computer science professor Sheldon Jacobson, there were 323 such killings – in which four or more people are killed in one incident – between January 2006 and October 2016. The mass killings appeared to be evenly distributed over that time, meaning their rate remained stable over the past decade, and did not spike during any particular season or year.

The professor used a decade’s worth of data from USA Today that was cross-checked by the FBI. He said his analysis also found public shooting sprees like the Las Vegas massacre are not the most common type of mass killing.

“Family mass killings are over three times more likely to occur than a public killing. So what we just saw in Las Vegas is actually not the most common type of mass killing,” Jacobson told CBS Chicago.