Sorry. Not trying to be difficult here, but there is no answer to your question for several reasons.

The West is the largest area of North America. Western historians often speak of "Many Wests" because the region is so diverse, geologically, environmentally, socially, etc. It is very difficult to speak in generalities when it comes to the region or its history.

The "Wild West" is more a figment of the imagination of various media than reality. This began with nineteenth-century extravagant newspaper articles published in the East, travel books and magazine articles, and dime novels. It then extended into the twentieth century with film and television. The West had its wild characteristics including wide open spaces where nature and Native Americans intimidated those who sought to move into and settle the region. There was also a tendency for the region to have a greater percentage of young men, and this often meant more crime and violence, but when this happened was extremely localized, so it is impossible to arrive at regional trends and timetables.

I have researched and published on crime in the West. How the West was settled depended a great deal on the environment and the type of economy that it attracted. Some communities tended to have a gender balance and others did not. Mining communities tended to attract larger numbers of young single men, and that could affect the nature of crime.

In mining communities of the Intermountain West there was a tendency for the first few years to see more alcohol-related crime. This translated into violence and alcohol-related deaths from fights. As these communities matured (assuming they didn't disappear as many mining communities did), crime shifted to petty crimes associated with the rising generation of teenage males. This included small time robberies, various forms of theft, and vandalism. Alcohol-related crimes and violence tended to decline as families were established.

Over the vast sweep of the region, communities were forming, maturing (or dissolving) at their own timetables. There was no region-wide progress in this matter, so there was no single peak year.

In addition, whatever can be summarized as typical for a mining community would have little equivalency for a coastal city, for a transportation hub, or for a town that served as a supply center for far-flung smaller settlements. Each type of community went through its own cycle of growth and maturation, each at its own pace.

Arriving at single figures for a region as vast and complex as the West is simply not possible. Sorry.