Defined by the crime rate per capita, Switzerland, Iceland, Denmark and Singapore are considered some of the safest countries in the world. A common characteristic in many of the countries with low crime rates is the higher ratio of police officers to population. In Singapore, a distinguishing and deterrent feature of law enforcement is the harshness of the penalties for crimes, including those not usually considered violent.
It is generally believed that countries with a fairly homogenous population also exhibit lower overall crime rates. This is based on the premise that it is easier to manage a country's internal affairs when the inhabitants share the same culture and a commonly accepted standard of conduct.
With regard to intentional homicide, which is the most violent of crimes, some of the lowest death-by-crime rates between the individual years 2008 and 2012 were reported to the United Nations Office on Drugs and Crime (UNODC) by Liechtenstein, Monaco, Singapore, Japan and Iceland. The two smallest countries in terms of population, Liechtenstein and Monaco, had zero homicides in 2012 and 2008, respectively, Iceland reported only one homicide in 2012, Singapore 11 in 2012 and Japan 442 in 2011.