Crime Basis

 Why Gun Ownership Rates Tell Us Little About Homicide Trends in America

What is the trend based on?
Culture based crime.

But amongst empirical criminologists the idea that legitimacy could explain macro-level variation in crime only gained some prominence in the late 1990s. In ‘Losing Legitimacy’ [Gary] LaFree (1998) argued that three key social institutions – family, economic, and political –motivate citizens to abide by the rules, participate in social control, and obey the law. When these social institutions are seen as unfair, useless, or corrupt, they lose legitimacy and subsequently the ability to maintain social control.

There is a lot more at the link.  You would do well to read it all and read it again.