In the nation as a whole with a black population of only 13%, they commit the majority of violent crimes (usually up in the 50th-60th percentile range). In cities, where their percentage of the population is much higher, their share of violent crime is also much higher.

In the city I live (not among the largest dozen), the black population is around 25%. A few years ago a look at homicides in which the suspect's race was known revealed about 90% of assailants were black. 25% is a relatively low percentage compared to many cities, so larger cities and cities with a higher black population are going to be higher — so that 95% approximation certainly seems realistic.

As a former mayor of New York City responsible for reducing crime there we can assume that's not a random number he just made up. In St Louis in 2017, for instance, 99% percent of murder suspects were black.