The number has actually been adjusted, recently.  Current research indicates that 1 out of 150 children are now identified as autistic, somewhere on a broad and colorful autistic spectrum.  For many of these children, especially if they are still rather young, outbursts are the only way they know how to cope with adverse circumstances in their constricted lives.  Reasoning is not an option.  Graduated increases in annoyance don't develop. For many of these children, it's zero to sixty in a heartbeat.

So the next time you see a child in such a riotous display, take a moment.  Consider the possibility that perhaps, this little person is trying to cope with more information than he is capable of, right then.  That he is unable to express distress in any other fashion than "a temper tantrum."  That his mind is not wired for a rational discussion of the current distress. 

And, maybe, say a prayer for his family, who are doing the best they can.