In my personal, qualitative experience as an official I have found the racial composition of my referee brethren to closely mirror the racial demographics of the United States as a whole, with a few exceptions. Here's the breakdown:

United States racial breakdown:
White: 63.7%
Black: 12.2%
Asian: 4.7%
Hispanic: 16.3%
Other races: 3.1%

The national white/black ratio is roughly 5 to 1 (.1915), which is perhaps comparable to the racial demographics of officials nationwide.

Indiana racial breakdown:
White: 80.0%
Black: 9.6%
Asian: 2.1%
Hispanic: 6.7%
Other races: 1.6%

The Indiana white/black ratio is roughly 8.3 to 1 (.1200).

In Indiana they send 9 officials to the regional to work 3 games. Thus, you can expect 7.92 white officials and 1.08 black officials at each site, disregarding travel/location assigning preferences. At East Chicago Central's site there were 8 white refs and 1 black ref (who worked the evening final), which is perfectly on par with Indiana demographics. This does not indicate a lower number of black refs working regional games however -- another regional was assigned 4 black officials. In fact the overall regional assignments for black officials in Indiana were 17/144, for 11.8%. That's almost exactly on par with Indiana's racial demographics.

I am very interested to hear what kind of demographic numbers the IHSAA will release.