In 2015, 1.4 million people were held in penitentiary institutions across Europe, which is 102,880 inmates less than the previous year.
The incarceration rate, which is often used as an indicator of how punitive anti-crime policies are, also fell by seven per cent from 124 inmates to 115.7 inmates per 100,000 inhabitants.
The figures are contained in the latest Council of Europe (CoE) annual penal statistics report, which was presented at a news conference in Brussels on Tuesday.
Reacting to the findings, Council of Europe Secretary General Thorbjørn Jagland said, “The drop in the overall number of people in prison in Europe is welcome. Increasing the use of alternative sentences does not necessarily lead to higher crime rates but can help to reintegrate offenders and tackle overcrowding.”
According to the Strasbourg-based CoE, significant reductions in the incarceration rate were recorded in Greece (-18.8 per cent), Croatia (-10.2 per cent), Denmark (-11.9 per cent), Northern Ireland (-9.7 per cent), the Netherlands (-9.5 per cent), Lithuania (-8.8 per cent), Romania (- 8.6 per cent) and Slovenia (-8.2 per cent).
On the other hand, the incarceration rate grew most in Georgia (+20.5 per cent), the former Yugoslav Republic of Macedonia (+12 per cent), Turkey (+11.6 per cent), the Czech Republic (+11.4 per cent) and Albania (+10.3 per cent).
The countries with the highest incarceration rates were Russia (439.2 inmates per 100,000 inhabitants), Lithuania (277.7), Georgia (274.6), Azerbaijan (249.3), Latvia (223.4), Turkey (220.4) and the Republic of Moldova (219.9).
The Netherlands (53) and some Nordic countries - namely Finland (54.8), Denmark (56.1) and Sweden (58.6) - appear to be those resorting less often to imprisonment and therefore registering the lowest rates, said the report.
Despite the overall reduction in the prison population in 2015, there was no progress at the pan-European level to reduce overcrowding, and the number of inmates remained above available places in one third of the prison administrations.
The situation improved in some countries and deteriorated in others. The number of inmates for every 100 available spaces in European prisons was 93.7 (93.6 in 2014), but the number of prison administrations suffering from overcrowding grew from 13 to 15.
Prison administrations that continued to be acutely overcrowded were those of the former Yugoslav Republic of Macedonia (138.2 inmates per 100 places), Spain (133.1), Hungary (129.4), Belgium (127), Albania (119.6), France (113.4) and Portugal (113). Other countries that continued to suffer from overcrowding were Serbia (106.4), Slovenia (105.8), Italy (105.6), Austria (103.3) and Romania (101.3).
Three prison administrations that did not suffer from overcrowding in 2014 did experience it in 2015: the Republic of Moldova and the Czech Republic.
On the other hand, the situation improved in Greece, where prison density fell from 121.4 inmates to 97.6.
The report said that almost one in four inmates (24.7 per cent) was serving a final sentence of one to three years.
The proportion of prisoners serving less than one year continued to be relatively high, although it fell from 15 per cent to 13.5 per cent. Prisoners subject to very long custodial terms, such as 10 years and over, life sentences and security measures represented 11.4 per cent of the total prison population.
In 2015, foreign inmates were 10.8 per cent of the total prison population, down from 13.7 per cent in 2014. In central and eastern European countries this proportion continued to be very small, while it was quite large in western European countries (in 16 prison administrations, one in every four inmates was a foreigner).
After natural causes, suicide was the most common cause of mortality in prisons, representing 25 per cent of all deaths. One in every four suicides was committed in pre-trial detention.