More People In the Spectrum Than We Know?

So I have talked to quite a few people, and have noticed some people who seem to fit certain traits linked to Autism Spectrum. So I was thinking that there are probably more people in the Spectrum than what is being reported. I think some people may have small or minute Autism traits so perhaps they pass for the norm or average person. I also wonder if there is some under reporting in the number of children diagnosed because of this same idea. This is just an idea I have and have no actual proof to back it up, but if you suspect that you may also be in the spectrum, or someone you know might be....perhaps this test may help shed some light on what you are suspecting - Autism Test for Adults. It is a very short test. Below I have included two books that may help.