150 to 16???!?
Has there been any negative Greek publicity around the school or possibly from the orientation leaders?? I seem to remember hearing about a prof from one of the schools up here (shadokat - I think it was Bloom?) putting anti-Greek literature in his department's information packet!
The way you describe it sounds like they are not just apathetic but openly hostile...that doesn't just happen for no reason. Something has to be behind it.