Unfortunately, I don't think there are historical numbers on Autism diagnoses that fit with our current understandings. The widespread recognition and frequent

Unfortunately, I don't think there are historical numbers on Autism diagnoses that fit with our current understandings. The widespread recognition and frequent diagnoses of autism is a relatively recent phenomenon. In other words, even if rate of incidence is declining, rate of diagnoses has sharply risen in recent decades, complicating the data.