During 2000–2005, an estimated 440,000 people per year emigrated from Africa, most of them to Europe. According to Hein de Haas, the director of the International Migration Institute at the University of Oxford, public discourse on African migration to Europe portrays the phenomenon as an "exodus", largely composed of illegal migrants, driven by conflict and poverty. He criticises this portrayal, arguing that the illegal migrants are often well educated and able to afford the considerable cost of the journey to Europe. Migration from Africa to Europe, he argues, "is fuelled by a structural demand for cheap migrant labour in informal sectors". Most migrate on their own initiative, rather than being the victims of traffickers. Furthermore, he argues that whereas the media and popular perceptions see irregular migrants as mostly arriving by sea, most actually arrive on tourist visas or with false documentation, or enter via the Spanish enclaves, Ceuta and Melilla. He states that "the majority of irregular African migrants "enter" Europe legally and subsequently overstay their visas". Similarly, migration expert Stephen Castles argues that "Despite the media hysteria on the growth of African migration to Europe, actual numbers seem quite small – although there is a surprising lack of precision in the data".