Absolutely!There is also the issue that what constitutes an autism diagnosis is not the same as it was 30 years ago. It is more "generous" today. As the defintion becomes more inclusive, more are included.
For that matter, nobody (at least not in the US) was even looking 30 years ago. Now everyone is looking. The more you look for something, the more you find.
Sometimes, if you look for it hard enough, you can even find it where it isn't.
And the number of resources put into testing, how people are selected for testing, etc etc etc.
Since the defn of autism shifts and changes constantly, with the diagnostics racing to keep up, it's hard to draw definitive conclusions on this beyond more people receiving a positive diagnosis.