Furthermore the early colonial states had weak effective control over their territories, which precluded efforts to widespread abolition. Abolition attempts became more concrete later during the colonial period. There were many causes for the decline and abolition of slavery in Africa during the colonial period include various economic changes, slave resistance, and colonial policies, some of which unintentionally ended slavery practices. Following conquest and abolition by the French, over a million slaves in French West Africa fled from their masters to earlier homes between 1906 and 1911. In Madagascar over 500,000 slaves were freed following French abolition in 1896. In response to this pressure, Ethiopia officially abolished slavery in 1932, Sokoto Caliphate abolished slavery in 1900, and the rest of the Sahel in 1911. Colonial nations were mostly successful in this aim, though slavery is still very active in Africa even though it has gradually moved to a wage economy. Independent nations attempting to westernize or impress Europe sometimes cultivated an image of slavery suppression, even as they, in the case of Egypt, hired European soldiers like Samuel White Baker's expedition up the Nile. Slavery has never been eradicated in Africa, and it commonly appears in African states, such as Chad, Ethiopia, Mali, Niger, and Sudan, in places where law and order have collapsed. Although outlawed in all countries today, slavery is practiced in secret in many parts of the world. There are an estimated 30 million victims of slavery worldwide. In Mauritania alone, up to 600,000 men, women and children, or 20% of the population, are enslaved, many of them used as bonded labour. Slavery in Mauritania was finally criminalized in August 2007. During the Second Sudanese Civil War people were taken into slavery; estimates of abductions range from 14,000 to 200,000. In Niger, where the practice of slavery was outlawed in 2003, a study found that almost 8% of the population are still slaves. Slavery and the slave trades had a significant impact on the size of the population and the gender distribution throughout much of Africa. The precise impact of these demographic shifts has been an issue of significant debate. The Atlantic slave trade took 70,000 people, primarily from the west coast of Africa, per year at its peak in the mid-1700s. The Arab slave trade involved the capture of peoples from the continental interior, who were then shipped overseas through ports on the Red Sea and elsewhere. It peaked at 10,000 people bartered per year in the 1600s. According to Patrick Manning, there was a consistent population decrease in large parts of Sub-Saharan Africa as a result of these slave trades.