Does anyone know of a relatively comprehensive listing of political violence in the USA since the mid 1990s?

When the topic of violent action and threats by right wingers comes up, their standard defense is to deny there is any such thing, and to claim that the real threat of violence is from the left. I’d like to find an online source that is fair and that documents ALL political violence and actions by anti-government groups. So far, Googling hasn’t brought one up. Is anyone aware of such a resource? If so, please post a link. If not, perhaps we will have to compile one of our own.