Excellent comment and catch. The 93% figure has been used in many blogs and has taken on a life of its own. Just do a search for "blacks killing blacks 93". The source article may be the one that begins:
A 2007 special report released by the Bureau of Justice Statistics, reveals that approximately 8,000 — and, in certain years, as many as 9,000 African Americans are murdered annually in the United States. This chilling figure is accompanied by another equally sobering fact, that 93% of these murders are in fact perpetrated by other blacks. The analysis, supported by FBI records, finds that in 2005 alone, for example, African Americans accounted for 49% of all homicide victims in the US — again, almost exclusively at the hands of other African Americans.
The source for the 93% figure may be this FBI table of Race and Sex of Victim by Race and Sex of Offender, 2009. If the black deaths are reduced by the 41 unknown, 2604 divided by 2826 is .92144, which would round up to 93%.
The FBI table shows 6,631 murders for 2009, while the CDC table shows 18,361 homicides for 2007. The CDC figure may be based on only the 16 states in the National Violent Death Reporting System, which would increase the homicides even more. It may be incorrect to assume the 93% figure holds true in different years and for this extended data set.