This is one of the worst attempts at an unbiased analysis of the issue that I've ever come across. Nothing of value can be garnered from this article.

Clearly Albania, a country with per capita GDP less than a tenth of the US is not a suitable comparison. No attempt has been made to account for income as a confounding variable.

The figures for Norway are predominantly driven by a single data point over the period compared to 67 mass shooting in the US over that same period. Surely this should be mentioned to allow for a proper interpretation of the data?

What about France, Switzerland, Finland? They're all above the US, and don't have low GDP per capita (although I'm not sure why we're supposed to associate poor countries with more shootings).