What I've been looking for....

Damn, they make it hard to find. But here we go. Arrest rates, per 100,000 persons, based upon race, grouped by violation.

From a sub-report generated by the FBI, I found the rates. They've broken it up strangely though. When aggregating, they simply use the categories "white," "total," and "minority." Then, there's a section broken down by age and race with those categories, and another section broken down by age and race between "black" and "other minority." So the data for white arrest rates is taken from the charts on pp. 59-63 and the arrest rates for blacks is taken from the data on pp. 65-69:

Drug Absue Violations Arrests (per 100k)

Whites under 18: 260.4
Whites over 18: 510.6
Blacks Under 18: 528.4
Blacks Over 18: 2228.0