Google Book result, you'll be after page 31, table 2.7. Doesn't include figures for high school dropouts though.

"Racial and ethnic diversity in America: a reference handbook" - 2000

http://books.google.com/books?id=xc-YEVDhC0MC&pg=PA30...

The scary table is number 2.9:

    homicide by firearm, per year, per 100,000 people

    age       10-14    15-19    20-24
    white      0.5      3.9      5.6
    hispanic   1.1     14.0     18.1
    black      1.8     29.1     55.6(!!)