Much of this is due to population growth. Switzerland’s population grew 28% over the same period. However, population growth doesn’t account for all of the increase in prison numbers. In 1988, there were 70 prisoners per 100,000. By 2017, the same figure was 17% higher at 82 per 100,000.

In 2017 there were 6,863 prisoners in Switzerland. 94% of them were men and 72% were foreign citizens.

The rate of incarceration among foreigners was more than seven times the rate of Swiss. Part of the difference can be explained by the different age profile of both groups. More crime is committed by young people and foreigners are typically younger. In 2017, 75% of prisoners were under 44 years old. In addition, men arrive in greater numbers than women – in 2017 for there were 114 male immigrants for every 100 female immigrants.

Incarceration rates across nationalities vary significantly. Citizens from some EU countries, such as Germany and the UK have lower rates than that of the Swiss population.

Others, such as Italians and Portuguese have rates around double those of Swiss nationals, while French citizens are close to four times as likely to end up in a Swiss prison as a Swiss. Many other EU countries like Croatia, Czech Republic, Denmark, Estonia, Finland, Latvia, Lithuania, Luxembourg, Malta, and Slovenia, had no citizens in Swiss prisons in 2017.

The average rate among non-EU citizens is around 13 times the rate for Swiss citizens. However, this rate hides wide variations. Rates are low for North Americans, who come in slightly below the Swiss rate. And, there is a long list of nations with only one or none of their nationals in a Swiss jail. This list includes countries such as Japan, Singapore, Australia, New Zealand, Saudi Arabia, Botswana, Nigeria and South Africa.