from 30 sub-Saharan countries totalled $187bn, exceeding those nations' external debts. Authors Leonce Ndikumana and James K. Boyce estimate that from 1970 to 2008, capital flight from 33 sub-Saharan countries totalled $700bn. This disparity in development is consistent with the model theorized by economist Mancur Olson. Because governments were politically unstable and new governments often confiscated their predecessors' assets, officials would stash their wealth abroad, out of reach of any future expropriation. Congolese dictator Mobutu Sese Seko became notorious for corruption, nepotism, and the embezzlement of between US$4 billion and $15 billion during his reign. Socialist governments influenced by Marxism, and the land reform they have enacted, have also contributed to economic stagnation in Africa. For example, the regime of Robert Mugabe in Zimbabwe, particularly the land seizures from white farmers, led to the collapse of the country's agricultural economy, which had formerly been one of Africa's strongest; Mugabe had been previously supported by the USSR and China during the Zimbabwe War of Liberation. Tanzania was left as one of the world's poorest and most aid-dependent nations, and has taken decades to recover. Since the abolition of the socialist one-party state in 1992 and the transition to democracy, Tanzania has experienced rapid economic growth, with growth of 6.5% in 2017. Foreign aid Food shipments in case of dire local shortage are generally uncontroversial; but as Amartya Sen has shown, most famines involve a local lack of income rather than of food. In such situations, food aid—as opposed to financial aid—has the effect of destroying local agriculture and serves mainly to benefit Western agribusiness which are vastly overproducing food as a result of agricultural subsidies. Historically, food aid is more highly correlated with excess supply in Western countries than with the needs of developing countries. Foreign aid has been an integral part of African economic development since the 1980s. The aid model has been criticized for supplanting trade initiatives. Growing evidence shows that foreign aid has made the continent poorer. One of the biggest critics of the aid development model is economist Dambisa Moyo (a Zambian economist based in the US), who introduced the Dead Aid model, which highlights how foreign aid has been a deterrent for local development. Today, Africa faces the problem of attracting foreign aid in areas where there is potential for high income from demand. It is in need of more economic policies and active participation in