From Politifact:
Two researchers — Jaclyn Schildkraut of the State University of New York in Oswego and H. Jaymi Elsass of Texas State University — analyzed mass shootings in 11 countries, covering the period from 2000-14. Aside from the United States, they looked at Australia, Canada, China, England, Finland, France, Germany, Mexico, Norway and Switzerland.
The United States has more mass shootings — and more people cumulatively killed or injured — than the other 10 nations combined, according to their research. While part of this is because the United States has a much bigger population than all but China, the difference can’t be explained by skewed population numbers alone.
When adjusted for population, the United States ranks in the upper half of their list of 11 countries, ranking higher than Australia, Canada, China, England, France, Germany and Mexico. The United States did rank lower than three countries — Norway, Finland and Switzerland — but they have populations so small that one or two mass-casualty events can produce a relatively high per capita rate.