Singapore has the biggest income gap among 23 rich nations surveyed in the book, The Spirit Level: Why Greater Equality Makes Societies Stronger, by Richard Wilkinson and Kate Pickett. This chart from the book shows the income gap between the richest 20 per cent and poorest 20 per cent of the population.
Singapore has the second highest number of prison inmates per 100,000 people, as this chart shows. The USA has the highest among the 23 nations surveyed.
Singapore's homicide rate is also higher than that of Japan, Norway, Austria, Spain, Ireland, Switzerland and New Zealand, according to this chart from the book based on the same UN surveys.