Human trafficking is defined by the United Nations Office on Drugs and Crime (UNODC) as "the recruitment, transport, transfer, harbouring or receipt of a person by such means as threat or use of force or other forms of coercion, of abduction, of fraud or deception for the purpose of exploitation". The UNODC approximates the number of victims worldwide to be around 2.5 million. UNICEF reports that since 1982 about 30 million children have been trafficked. Trafficking for sexual slavery accounts for 79% of cases, with the majority of victims being female, of which an estimated 20% are children. Women are also often perpetrators as well.