Aside from the fact that the numbers are wrong, what is the point being made here in regards to the killing of Trayvon Martin? By my read, the point being made here is that blacks are violent people, and perhaps that Zimmerman was more justified in his actions.

I think posts like this are severely misguided, and here is why:

A large part of black culture in the US has very serious problems. Bill Cosby has made a great effort to underline what they are, which includes undervaluing education, glamorizing materialism, normalizing sexism, normalizing teen pregnancy, and normalizing single-parent child-rearing. In combination, all these factors help to keep many black Americans on the bottom of the socio-economic ladder, and they inherit all that comes with that.

But, in addition to this, the relationship between whites and blacks in the US has very serious problems. Some whites promote messages (articles like this) that demonize blacks, and they don't consider the inequities that blacks have suffered are enough to explain the current condition of black culture. They teach this to their children, and practice soft racism by moving away from blacks and by preferring to interact with whites, and allowing stereotypes to color their judgement. On the flipside, blacks embrace a cynicism towards whites and white culture that encourages an ongoing divide between the races, and they surrender to the system by combating it in cathartic but superficial ways.

In short, the awful context surrounding the Trayvon Martin killing is one built by whites and blacks, and posts like this perpetuate it.