How has crime changed over the years?

To answer this question, you must first establish what crime is.

Crime is relative to what is considered 'bad' or 'negative' at the time and place.

For instance, during the 1930s, the United States was a prohibitionist state, meaning they forbid alcohol. Thus, somebody who engaged in the consumption of alcohol would be committing a crime, though today, it's only a crime to consume alcohol if you're under 21, or driving, etc.

So, crime has changed only to coincide with the current laws and regulations.