30th July was World Day Against Trafficking in Persons. The official UN website provides background on the need for the day and related United Nations publications.
Other useful sources for facts include:
UNODC Global Report on Trafficking in Persons 2018 provides data on types, victims and regional flows. It records that 70% of the detected trafficking victims worldwide are female. The share of domestic victims, persons trafficked within their own country, among those detected has more than doubled from 27 per cent in 2010 to 58 per cent in 2016.
Global Estimates of Modern Slavery: Forced Labour and Forced Marriage. The International Labour Organization’s latest report on Human Trafficking, published in 2017, focussed on two main issues: forced labour and forced marriage.
The Counter-Trafficking Data Collaborative intends to provide a worldwide gateway to statistical data on human trafficking. It is supported by the IOM and publishes harmonized data from counter-trafficking organizations around the world. It was launched in November 2017.
Trafficking in Persons report – published by the US government surveys efforts by governments worldwide to combat trafficking. There is also an American national service: National Human Trafficking Hotline Statistics (USA)
End Slavery Now is a US-based organisation but its website contains campaign materials, news and links to reports which are international in scope.
The Human Trafficking Foundation grew out of the All-Party Parliamentary Group on Human Trafficking and Modern Slavery. It includes details of the problem and policy efforts.
The National Crime Agency collects statistics.