That's a bit of a disparity.
Source: http://www.washingtonpost.com/blogs/wonkblog/wp/2012/12/14/n...
I pulled the above statistic because of the specific context of mass shootings. But hey, at least you got a pithy retort out of it.
Firearm related death rate, per 100K of population.
http://en.wikipedia.org/wiki/List_of_countries_by_firearm-re...
US: 9.0 Switzerland: 6.4 Finland: 3.64 Germany: 1.1 UK: 0.25
...
While guns may have increased the severity of the damage, the lack of a gun did little to stop a similar event from taking place. People that want to do harm to others will find a way, and while there's something to be said for trying to lessen how much damage they can do, that seems to be a poor attempt at treating the symptom rather than the disease.
Put another way: let's look at the overall violent crime rates by country instead. Here we go: https://en.wikipedia.org/wiki/List_of_countries_by_intention... US ranks at 4.2/100k
I'd also like to point out your selective data pull is very misleading (whether it was intentional or not I don't know; I'll give you the benefit of the doubt). Of those 9 deaths per 100k, 5.75 are suicides and 0.27 are unintentional; only 2.98 were murders (so we have nearly 75% of our murders by gun, but overall a quite low murder rate compared to over a dozen countries at 30+/100k and four over 50). Also from missing from your quote - the US is #12 in terms of firearm deaths per capita, not #1 as your data implies.
The only data that is really relevant to gun control arguments are murders that would not have been possible without a gun and (probably more relevant) accidental gun deaths. Anyone sufficiently determined to kill themselves will find any number of ways, so that's almost completely irrelevant to the discussion.
"...poor attempt at treating the symptom rather than the disease". Sorry, the symptoms (i.e. lots of people dead) are the problem here.
My data pull was primarily for the countries mentioned earlier, I added some others I find relevant because I have experience living there (never been to Finland). I did not imply the US was #1, the extract was obviously a very short one.
The Wikipedia page you cite tells essentially the same story as the Washington Post article: of the OECD countries, the US is by far the most violent, more than 4x more than Germany, for example. Take a look at the countries surrounding the US in the statistic! If you're not embarrassed, you're not paying attention.
The "would not have been possible without a gun" argument is specious, as is "anyone sufficiently determined" argument for suicides: you are assuming that anyone with a suicide attempt is sufficiently determined, as is someone wanting to kill someone. This is a fallacy, both logically and from what the data show.
Not being able to stop everyone is no excuse for not even trying to stop those that can be stopped (or reducing the damage...heck if no-one gut hurt, would the "rampage" even be a problem??)
If Wikipedia is correct, this was a whole series of attacks, sometimes with multiple assailants, with each attack having far fewer fatalities, so the point about reducing the damage stands.
Still awful.
Luxembourg (total population 1/2 million) has the higher variance you mention, the rest of are pretty stable.
It certainly looks like Scandinavia and the UK might have a problem. Europe as a whole still has fewer than the US for a similar population but it is high. None for China, India or Brazil. So it is not just about normalisation...
The most recent UK shooting of note, Derrick Bird, used a double-barrelled sawn-off shotgun and a .22 (bolt-action) rifle. Would it have been worse if he'd had handguns and semi-automatic rifles? We'll never know, but he did try to acquire another firearm mid-rampage so he clearly felt like he needed more firepower.
I'd agree that Scandinavia has a bigger problem (EU would be at 2 without Finland). (Norway is not part of the EU, and I also didn't count the US soldier going on a rampage in Afghanistan).
Of those mentioned in the list; 6 in the past 25 years are in Europe. 3 shootings, on this list alone, happened in the US in the past 6 months! Most European countries probably haven't had any of this type of thing happen in the past 25+ years.
Remember when there were huge epidemics of suicide and Satanic ritual abuse in the 80s? Or rather, people said there were. In reality, suicide rates remained mostly flat, even declining slightly overall, and the evil Satanic cults were a myth. So, be careful about postulating something deeply wrong with our culture, when there may well be another explanation.