This is pure sleight of hand meant to deceive.
When incident can be defined arbitrarily and possibly include both a gun massacre and a spray painted swastika as equal events, this stat is incredibly deceptive.
What's the ratio when you count deaths? I'm on mobile but iirc it's about 90% killed by Islamic terrorists.
53% Islamist, 47% (other, as Islamist actually fit this description too) far-right, 0% other. (So the ratio is closer to 1:1 than the 9:1 you suggest)
http://www.politifact.com/truth-o-meter/article/2017/aug/16/...
If we're going to talk about murders in a more general sense, you have to start looking at populations and then note that whites in the US are far, far more prevalent than Muslims.
But it's not murder in a general sense, it's murder by white supremacists.
> It is unfair if we're talking about terrorism, because prison murders are not terrorism.
Sure it is, if it's political, ie about white supremacy.
Terrorism:
> the unlawful use of violence and intimidation, especially against civilians, in the pursuit of political aims.
> According to the Government Accountability Office of the United States, 73% of violent extremist incidents that resulted in deaths since September 12, 2001 were caused by right wing extremists groups.[41][42]