number of unaggregated class C's in swamp?

How would one go about determining how many /24 /23 ... /19 unaggregated advertisements are in the swamp. I assume it would have to be examined by AS, and look for multiple paths to find multi-homed, but it should be doable with the current database, shouldn't it? Has someone already done this? I asked Merit yesterday, and they don't seem to have the tools. Bill.Simpson@um.cc.umich.edu Key fingerprint = 2E 07 23 03 C5 62 70 D3 59 B1 4F 5E 1D C2 C1 A2