According to a study done in 2006, approximately 800,000 people are trafficked across national borders each year, and millions trafficked inside their own countries. This includes all types of human trafficking, although trafficking for prostitution is thought by some to make up a large portion of trafficking. Because it is illegal, it is hard to find out the real number of women or children forced into sex work. The study estimated that eighty percent of transnational victims are women and girls and up to half of them may be minors (meaning not adults). 