“The precise number of people lured into trafficking is unknown. Between the smugglers’ efforts to avoid detection and the low priority given by most governments to monitoring and preventing trafficking, estimates vary widely, notes the UN human rights commissioner’s special rapporteur on human trafficking, Joy Ezeilo. She puts the total number of people trafficked globally last year at about 2.5 million, including more than 1 million children. It is also big business, earning the gangs upwards of $10 bn a year, reports UNICEF.”
Here's the article that quote is from: http://blogs.the-american-interest.com/wrm/2009/12/02/john-brown-dead-slavery-marches-on
As they say, read it all.