(CNN) There's no one commonly accepted definition of a mass shooting. But whatever criteria you use, the conclusion's the same: They are far too common.

If you go with the narrowest definition ...

The government has never defined "mass shooting" as a standalone category. Let's go with the, from the Congressional Research Service : a shooting in which a gunman ...

That definition rules out the Congressional baseball practice shooting or the incident at the UPS facility this week because neither gunman killed four people. In last week's Orlando shooting spree , the gunman killed five people -- but that attack doesn't count either because police say he targeted his victims.

Using that narrow definition, from January 1 to June 14, we have seen 8 deadly mass shootings.

That's an average of 1.3 mass shootings a month.

If you go with the raw numbers ...

four or more people are wounded or killed. What if you didn't rule out motive and just considered the casualty count? According to the non-profit Gun Violence Archive , which compiles data from shooting incidents, a "mass shooting" is any incident where

By that definition, from January 1 to June 14, we have seen 154 mass shootings.

That averages to 6.7 mass shootings a week.

It's troubling however you look at it

Whatever definition you consider, the instances are too depressingly frequent.

nearly a third of the world's mass shootings took place in the US. From 1966 to 2012,of the world's mass shootings took place in the US. This is according to a study last year that used the Congressional Research Service definition of "mass shooting."

It surveyed 292 incidents and found 90 of them occurred in America. Put another way: While the US has 5% of the world's population, it had 31% of all public mass shootings.

Editor's note: A sentence in an earlier version of this article incorrectly characterized how the Gun Violence Archive defines a mass shooting. According to the non-profit Gun Violence Archive, which compiles data from shooting incidents, a "mass shooting" is any incident where four or more people are wounded or killed. If the shooter dies in the incident, the Archive doesn't include that person in its tally.