Per registered firearm? Like most statistics, that stat is designed to prove the predetermined point of whoever invents it. In other words, it is blatantly misleading.
Many american firearms are not registered because we used to enjoy a lot of freedom in this country. We are often not required to register, so your stats are dangerously misleading. For reference...there are 12 firearms in my home. Many are used for one form of hunting or another, though several are of the variety that make gun control lobbyist cry themselves to sleep at night. Several have passed through the hands of generations of my family and none of them are registered.
I am not arguing against the fact that America can be a violent country though. That is certainly true. We are not a passive people.....thank god.