Why do tens of thousands of sub-saharan africans try to cross the mediterranean each year?

According to different estimates, between 65,000 and 120,000 sub-Saharan Africans enter the Maghreb (Mauritania, Morocco, Tunisia, Algeria, and Libya) yearly, of which 70 to 80 percent are believed to migrate through Libya and 20 to 30 percent through Algeria and Morocco. Several tens of thousands (not hundreds of thousands, as media coverage might suggest) of sub-Saharan Africans try to cross the Mediterranean each year.