On Wednesday, Americans woke up to news of yet another mass shooting, this time in San Bernardino, California. Fourteen are dead and 17 were injured when gunman stormed a social services center.

This interactive map from the Mass Shooting Tracker shows where and when those shootings occurred, providing contextual details about each case, and it also includes figures—the number of fatalities, the number of those injured, and some background information about the incidents as well. 

Vox - vox.com

Contrary to what we might assume about mass shootings given their apparent prevalence in mainstream media, it is not a recent phenomenon. After the Sandy Hook shooting, the Boston Globe's James Alan Fox looked at data from the FBI and police reports and found that, between 1980 and 2010, there has not been an increase in the occurrence of mass shootings.

The definition of a mass shooting is, in this case, a gun-related incident in which three or more people are shot. The Globe reported that an average of 30 mass shootings happen annually, with 100 people killed each year.

"Without minimizing the pain and suffering of the hundreds who have been victimized in senseless attacks, the facts say clearly that there has been no increase in mass killings, and certainly no epidemic," Fox wrote."Occasionally, we have witnessed short-term spikes with several shootings clustering close together in time."

The Boston Globe - boston.com

The Washington Post took a different approach to their data analysis on mass shootings in America, using an amended definition of the term. If you think about mass shootings as an incident in which four people are shot, rather than killed (as the FBI definition goes), then there have been more than 200 of these tragedies in 2015 alone. That's almost one mass shooting per day this year.

This year, we witnessed the Charleston shooting, where self-proclaimed white supremacist Dylann Roof fired into a historically Black church and killed nine parishioners; this month, we are grappling with two additional, high-profile shootings—one at a military base in Chattanooga, Tennessee, which left four Marines and one sailor dead, and then the theater shooting in Louisiana. Then there was the mass shooting at a community college in Oregon in October.

But based on reports from various databases and media organizations, these incidents represent only a small fraction of the mass shootings that occur every year.