The only crime rate data which is really reliable is the murder rate. This peaked in 1991 and has been generally stable (not steadily declining) since 1999, with a spike during the COVID-19 pandemic. Almost all murders do get reported and counted.

https://www.consumershield.com/articles/murder-rate-by-year

I don't trust the statistics for lesser crimes because so many of the victims never file a report. In many cities the police now subtly discourage people from filing reports because they don't want to deal with the paperwork or have their statistics look bad. But I think we can generally use the murder rate as a proxy for the overall level of criminality.