The Rise in ASD
The CDC used reporting sites to calculate the totals below. There has been a rise from 1 in 150 children reported in 2000 to 1 in 36 children reported in 2020. Almost every year, there are more children diagnosed with ASD than the year before. The rise in diagnoses is currently expected to continue in an upward trend.
https://www.cdc.gov/ncbddd/autism/data.html
The birth year and the number of autism spectrum disorders diagnosed per 1,000 children
When looking at statistics, you can expect that the numbers will not be completely accurate. Most of the time, there are unreported cases, which makes it impossible to be completely accurate. The takeaway from this information is just that there has been a steady rise in reported cases over time. There are many theories on why, but currently we only have correlation and not causation.