The Global Slavery Index provides a map, country by country, of the estimated prevalence of modern slavery, together with information about the steps each government has taken to respond to this issue. This information is about the problem of modern slavery and adequacy of the response in 167 countries.
The index is published by the Walk Free Foundation, an Australian organisation.
Modern or contemporary slavery refers to individuals currently caught in the slave trade industry.
North Korea ranked worst, with one in 20 citizens living in slavery conditions, or 4.4% of the country's population of 25 million.
Slavery also exists in advanced democratic nations, in the form of forced work of various kinds, including forced prostitution.
All European countries criminalise slavery, and Croatia, the Netherlands, Britain, Sweden and Portugal are pointed out as the countries with the best response to this problem.