perhaps there is a conspiracy i dont know but perhaps it could be in countries that women are afraid for there lives everyday that it may be easier for men to getup and disappear /leave unnoticed then a women who is slave to there society or maybe old people that cant walk 10 miles arent in the big mix also-got me
this is interesting
http://unstats.un.org/unsd/genderstatmanual/International-migration.ashx
At the global level, about half of international migrants are women, a share slightly higher than in the past (United Nations, 2010a, 2010b). However, there are great variations by region. For example, countries in Africa, West Asia and South Asia have a lower share of women among migrants (United Nations, 2010a, 2010b). The share of women among migrants in OECD countries is higher among migrants from Asia and lower among migrants from Africa and some countries in Latin America (OECD, 2008). The relative propensity of women in Latin American countries to migrate across international borders is higher in matriarchal societies (such as the Dominican Republic and Nicaragua) and lower in those that are patriarchal (such as Costa Rica Mexico) (Massey, Fischer and Capoferro, 2006; OECD, 2008). Furthermore, being married or in a union greatly reduces the probability of migration for women living in patriarchal societies, while there is no such effect in a matriarchal context.