[mod note] thread revival- this thread is about 6 years old. Good job making use of the search function!
Casual research during the last 12 months tells me the washout rates at Great Lakes Airlines and Trans States Airlines are greater than 10%, they are probably in the neighborhood of 30-40% per class. They do not want to spend much money on training, it is cheaper to replace problem students than to bring them up to the standard.
Anecdotal reports on ExpressJet, ASA, and Skywest in the same time tell me they have less than 10% per class in washouts apiece, all 3 are fairly strong in their training efforts, and they tend to work with problem students.
Someone earlier in this thread made the point more than 10% washout rate indicates some sort of trouble or weakness in the hiring and/or training departments, while the lower figure for washouts cannot reasonably be less than about 5% per class due to unavoidable issues during training.