* Number of jailed per 100K, number of homicides per 100K, number of police per 100K.
* Perceptions of criminality, accessibility of weapons of minor destruction.
* Number of deaths from organized conflict (internal and external)
* Military capability & sophistication, military expenditure as percentage of GDP.
* Relations with neighboring countries.
Top of the list: New Zealand (score 1.18), Iceland, Japan, Austria, Norway, Ireland, Denmark, Luxembourg, Finland, Sweden.
Bottom: Congo, Chad, Georgia, Russia, Israel, Pakistan, Sudan, Afghanistan, Somalia, Iraq (score 3.40).
USA? It's at 85th place with a score of 2.06. Nice colorful map at the link.