Autism

I just finished reading an article on a camp for kids with autism to help them gain better social skills and I have this one question, "Why does it seem like there are so many more children being diagnosed with autism today than fifteen years ago when I was a tot?"
In all fifteen years of my education, I was only in class with one autistic kid. Thats it. My sister, who works as a camp counslor, says there's atleast one or two autistic children in each weekly camp session. Why is it so much common today than it was ten years ago? I've heard somewhere that the chances of a child being diagnosed with autism today are only 1 in 150, which is remarkably high considering that being diagnosed with having autism forty years ago was like 1 in 1,000.
So why is it that autism rates are so high these days? Some people like to blame unhealthy diets and artificial flavoring to food as a cause of autism, while others blame vaccinations. I've also heard that autism has to something with genetics(anyone read the story of a family with six autistic children in People magazine about a year ago?). Maybe its a mixture of all three? Maybe its due to some genetic mutation that some children are more prone to developing autism than others? Who knows? But honestly, to tell you the truth I don't think that vaccinations are solely the cause of autism(sorry Jenny McCarthy). Vaccinations have been around for a very long time, but these stories of families blaming vaccinations on their child's autism are pretty recent. Now I don't downright disagree with these people, I'm just saying that I don't think vaccinations are the only cause of autism in children. I mean these people could be right that after having four or five vaccinations at one time can cause autism, but I think there have many children before who've had five vaccinations at one time who are nowhere near being autistic and five vaccinations didn't turn them autistic. Now I don't want any parent autism advocate groups going after me and certaintly I don't want Jenny McCarthy either, but I think its silly just to blame vaccinations as a cause of autism. As I said before, maybe some are more genetically prone than others or maybe it could be the pesticides ands added ingredients in food that some blame as a cause of autism? Who really knows? My only question will is, are the chances of kid being diagnosed with autism in ten years(when I'll hopefully be married), going to be higher than they are today? Or was autism rates always this high, just more easily recognized today than forty years ago.