(Newser) – The Newtown killings have jolted the nation—and USA Today offers a stat that's bound to do the same. Its analysis of FBI records from 2006 to 2010 shows that a mass killing occurs in our nation, on average, every two weeks. It defines mass shooting as the FBI does, as one in which at least four people are murdered. Over those five years, 156 such attacks occurred, killing 774; at least 20% of those victims were under the age of 13. Among its other findings:

About 25% of the attacks featured multiple killers

A third involved no guns; fire, knives, or blunt objects were among the alternate murder weapons

These killers are older than the typical murderer: average age is 32

Still, mass murders make up just 1% of all murders that occurred over the period. USA Today notes that, per CDC records, migraines and falls out of chairs killed more people.

Click to see a chart of all 196 fatal school shootings that have occurred in America since 1980 . (Read more Newtown, Connecticut stories.)